|
Magnetic phenomena
are omnipresent in the modern world. The Nobel prize in Physics (2007) was
awarded for studies of giant magnetoresistance to A. Fert and
P. Grünberg; their discoveries were soon implemented in hard drives
(see picture, courtesy of IBM Germany). Learn more about the current
research into magnetic materials, basic or
applied.
Antti Riisiö, Mikko M. Hänninen, Reijo Sillanpää
Syntheses and Structural Study of Novel Tetranuclear Bis(phenoxido)-Bridged CuII Metal–Organic Macrocycles [Full Paper]
The geometrical parameters and magnetic properties of structurally interesting metal–organic macrocycles {[Cu4(L)2]·xS and [Cu4(L)2(H2O)2]·xS} can be varied drastically by changing the crystallization solvent. Six novel structures are reported along with their calculated magnetic coupling constants.
Ding-Bang Xiong, Norihiko L. Okamoto, Takeshi Waki, Yufeng Zhao, Kyosuke Kishida, Haruyuki Inui
High-TC Ferromagnetic Semiconductor-Like Behavior and Unusual Electrical Properties in Compounds with a 2×2×2 Superstructure of the Half-Heusler Phase [Full Paper]
Doing things by halves: A series of new compounds that crystallize in the 2×2×2 superstructure of the half-Heusler phase have been obtained (see figure). In these new compounds, abnormal electrical properties and a ferromagnetic semiconductor-like behavior above room temperature have been observed.
Gong-Jun Chen, Yun-Nan Guo, Jin-Lei Tian, Jinkui Tang, Wen Gu, Xin Liu, Shi-Ping Yan, Peng Cheng, Dai-Zheng Liao
Enhancing Anisotropy Barriers of Dysprosium(III) Single-Ion Magnets [Communication]
Magnetic personality: The incorporation of a bulky auxiliary ligand in β-diketone-based dysprosium(III) single-ion magnets (SIMs) remarkably increases the anisotropic barriers, representing a promising route toward the design of higher-anisotropic-barrier SIMs (see scheme).
Qingchen Dong, Guijun Li, Cheuk-Lam Ho, Mahtab Faisal, Chi-Wah Leung, Philip Wing-Tat Pong, Kun Liu, Ben-Zhong Tang, Ian Manners, Wai-Yeung Wong
A Polyferroplatinyne Precursor for the Rapid Fabrication of L10-FePt-type Bit Patterned Media by Nanoimprint Lithography [Communication]
A polyferroplatinyne polymer can be patterned on the surface of Si wafer in ordered nanoline or nanodot shapes with PDMS molds through nanoimprint lithography (NIL), and subsequent thermal treatment gives rise to the nanopatterned arrays of L10-FePt nanoparticles with the same periodicities. The method offers excellent potential to be utilized in the simple and rapid fabrication of bit patterned media for magnetic data recording.
Dachuan Liang, Jianqiang Gu, Jiaguang Han, Yuanmu Yang, Shuang Zhang, Weili Zhang
Robust Large Dimension Terahertz Cloaking [Communication]
A large scale homogenous invisibility cloak functioning at terahertz frequencies is reported. The terahertz invisibility device features a large concealed volume, low loss, and broad bandwidth. In particular, it is capable of hiding objects with a dimension nearly an order of magnitude larger than that of its lithographic counterpart, but without involving complex and time-consuming cleanroom processing.
Giuseppe Cucinotta, Mauro Perfetti, Javier Luzon, Mael Etienne, Pierre-Emmanuel Car, Andrea Caneschi, Guillaume Calvez, Kevin Bernot, Roberta Sessoli
Magnetic Anisotropy in a Dysprosium/DOTA Single-Molecule Magnet: Beyond Simple Magneto-Structural Correlations [Communication]
Magnetic moments: The orientation of the title single-molecule magnet was investigated by magnetic single crystal and luminescence characterization, supported by ab initio calculations, and was found to be governed by the position of the hydrogen atoms of the apical water molecules. This finding suggests that simple magneto-structural correlations can give misleading clues for research in molecular magnetism as well as in the design of MRI contrast agents.
Soichiro Tottori, Li Zhang, Famin Qiu, Krzysztof K. Krawczyk, Alfredo Franco-Obregón, Bradley J. Nelson
Magnetic Helical Micromachines: Fabrication, Controlled Swimming, and Cargo Transport [Communication]
A simple and general fabrication method for helical swimming micromachines by direct laser writing and e-beam evaporation is demonstrated. The magnetic helical devices exhibit varying magnetic shape anisotropy, yet always generate corkscrew motion using a rotating magnetic field. They also exhibit good swimming performance and are capable of pick-and-place micromanipulation in 3D. Cytotoxicity of the devices was investigated using mouse myoblasts.
Martin Vérot, Nicolas Bréfuel, Jacques Pécaut, Cyrille Train, Vincent Robert
Seeking Hidden Magnetic Phenomena by Theoretical Means in a Thiooxoverdazyl Adduct [Full Paper]
When temperature does matter: The mismatch between the crystal structure of a thioverdazyl adduct and the apparent S=1/2 one-dimensional antiferromagnetic behavior of the magnetic susceptibility is analyzed with ab initio methods. In such organic-radical-based materials, the underlying magnetic behavior is shown to be much more subtle.
Jesús Ferrando-Soria, Rafael Ruiz-García, Joan Cano, Salah-Eddine Stiriba, Julia Vallejo, Isabel Castro, Miguel Julve, Francesc Lloret, Pedro Amorós, Jorge Pasán, Catalina Ruiz-Pérez, Yves Journaux, Emilio Pardo
Reversible Solvatomagnetic Switching in a Spongelike Manganese(II)–Copper(II) 3D Open Framework with a Pillared Square/Octagonal Layer Architecture [Full Paper]
Molecular magnetic sponges: A new oxamato-based mixed-metal–organic framework (shown here) reversibly switches from a crystalline hydrated phase with long-range ferromagnetic ordering at a critical temperature (Tc) of 22.5 K to an amorphous dehydrated phase at Tc=2.3 K. The dehydration/rehydration process is accompanied by large changes in crystal volume (ca. 45 %) and color.
Sunghun Lee, Juneho In, Jung-Won Chang, Kwanyong Seo, Myung-Hwa Jung, Jinhee Kim, Bongsoo Kim
Magnetotransport Properties and Kondo Effect Observed in a Ferromagnetic Single-Crystalline Fe1−xCoxSi Nanowire [Full Paper]
Down to the wire: Ferromagnetic single-crystalline Fe1−xCoxSi nanowires (NWs) were synthesized by means of a vapor transport method with no catalyst. The magnetotransport properties of the Fe1−xCoxSi NW reveal negative anisotropic magnetoresistance owing to dominant spin-down electrons. The various results (see figure) are of interest for spintronic devices.
Wei Gao, Daniel Kagan, On Shun Pak, Corbin Clawson, Susana Campuzano, Erdembileg Chuluun-Erdene, Erik Shipton, Eric E. Fullerton, Liangfang Zhang, Eric Lauga, Joseph Wang
Cargo-Towing Fuel-Free Magnetic Nanoswimmers for Targeted Drug Delivery [Full Paper]
Fuel-free nanomotors are essential for future in-vivo biomedical applications. The first example of towing drug-loaded magnetic polymeric particles using magnetically driven fuel free flexible nanomotors is described. The effect of the cargo size upon the swimming performance is evaluated experimentally and compared to a theoretical model. Potential applications of these cargo-towing motors are demonstrated by using the directed delivery of drug-loaded microparticles to HeLa cancer cells in biological media.
Yanlan Liu, Kelong Ai, Jianhua Liu, Qinghai Yuan, Yangyang He, Lehui Lu
A High-Performance Ytterbium-Based Nanoparticulate Contrast Agent for In Vivo X-Ray Computed Tomography Imaging [Communication]
Enlightening particles: A contrast agent for in vivo X-ray computed tomography (CT) imaging is composed of an Yb-based nanoparticle (NP) that is stabilized with oleic acid and modified with the biocompatible polymer DSPE-PEG 2000 (see picture). The contrast agent exhibits long circulation time in vivo and low toxicity and is also much more effective than a clinical iodinated agent.
Galina S. Matouzenko, Erwann Jeanneau, Alexander Yu. Verat, Yannick de Gaetano
The Nature of Spin Crossover and Coordination Core Distortion in a Family of Binuclear Iron(II) Complexes with Bipyridyl-Like Bridging Ligands [Full Paper]
The structure–property correlations for a family of binuclear spin crossover (SCO) complexes confirm the key role of [FeN6] octahedral distortions, which are caused by crystal packing and strain effects from terminal and/or bridging ligands, in the generation of different types of SCO behavior (one-step, two-step, partial 50 % transition).
Judith Schlagnitweit, Steven W. Morgan, Martin Nausner, Norbert Müller, Hervé Desvaux
Non-Linear Signal Detection Improvement by Radiation Damping in Single-Pulse NMR Spectra [Article]
Positive feedback: The precessing magnetizations of the two species Ma and Mb can influence each other through the feedback field of the detection circuit (radiation damping field, see picture). The resulting spectra exhibit surprising line shapes, such as the appearance of a hole, allowing detection of hidden tiny signals.
Ross McIntosh, Somnath Bhattacharyya
The Kondo effect in reduced graphene oxide films [Rapid Research Letter]
The Kondo effect is demonstrated in reduced graphene oxide prepared using organic acid reduction. Resistance vs. temperature measurements show a metal–insulator transition at 30 K. Fits of the data showed a Kondo temperature of 2.6 K which is consistent with the characteristic temperature determined from negative magnetoresistance measurements. This study illustrates the viability of reduced graphene oxide for spintronic applications.
Ya-Qiu Sun, Lin Wu, Lan-Lan Fan, Guo-Ying Zhang, Yan-Yan Xu, Dong-Zhao Gao
Heterometallic Polynuclear Complexes of Macrocyclic Oxamide with Pyrazine-2, 3-dicarboxylic Acid: Synthesis, Crystal Structure, and Magnetic Properties [Article]
Da-Yu Wu, Wei Huang, Laiguo Wang, Genhua Wu
Synthesis, Structure, and Magnetic Properties of a Dinuclear Antiferromagnetically Coupled Cobalt Complex [Article]
Zhiguang Wang, Ravindranath Viswan, Bolin Hu, V. G. Harris, Jie-Fang Li, D. Viehland
Phase-controlled epitaxial growth of iron oxide thin films on MgO(001) and LaAlO3(001) substrates [Rapid Research Letter]
This article studies the substrate controlled phase stability of iron oxides. Epitaxial α-Fe2O3 was grown on LaAlO3 while γ-Fe2O3 could be stabilized on MgO substrate. The substrate template could tune the crystal lattice and rotate atom angles through strain effect, resulting in epitaxial thin films with different phase stability, electric and magnetic properties. These findings may help in building novel devices with controllable properties through strain from the substrate.
Zhiguang Wang, Ravindranath Viswan, Bolin Hu, V. G. Harris, Jie-Fang Li, D. Viehland
Tunable magnetic anisotropy of CoFe2O4 nanopillar arrays released from BiFeO3 matrix [Rapid Research Letter]
This Letter studies the BiFeO3 (BFO) strain effect on the magnetic properties of CoFe2O4 (CFO) nanopillars in self-assembled BFO–CFO thin films. Strain in the interface will affect the spontaneous magnetization in CFO, and the magnetic exchange between antiferromagnetic BFO and ferromagnetic CFO also affects the magnetic properties of CFO. Thus, removal of the BFO matrix results in a dramatic change in the magnetic properties of the CFO nanopillars.
Célia S. Bonnet, Frédéric Buron, Fabien Caillé, Chad M. Shade, Bohuslav Drahoš, Laurent Pellegatti, Jian Zhang, Sandrine Villette, Lothar Helm, Chantal Pichon, Franck Suzenet, Stéphane Petoud, Eva Tóth
Pyridine-Based Lanthanide Complexes Combining MRI and NIR Luminescence Activities [Full Paper]
Bimodal application: Pyridine-based polyamino–polycarboxylate ligands (see figure) ensure non-toxicity as well as advantageous magnetic and luminescence properties for the corresponding Gd3+ and near-infrared-emitting lanthanide complexes.
Chenglong Hu, Yujie Chen, Xudong Chen, Bin Zhang, Jin Yang, Juying Zhou, Ming Qiu Zhang
Enhancement of Photoresponse Properties of Conjugated Polymers/Inorganic Semiconductor Nanocomposites by Internal Micro-Magnetic Field [Full Paper]
Hybrid materials: The internal micro-magnetic field (IMMF) effect in Fe3O4@PANI-CdS photoelectric active hybrid nanocomposites was found to improve their power conversion efficiencies (PCE) by increasing the number of singlet polaron pairs through field-dependent intersystem crossing (ISC). The PCE of as-prepared nanocomposites was improved from 1.135 to 3.563 % with changes in IMMF from 0 to 1.2×10−3 emu g−1 (see figure).
Joseph Park, Jaemoon Yang, Eun-Kyung Lim, Eunjung Kim, Jihye Choi, Joo Kyung Ryu, Nam Hee Kim, Jin-Suck Suh, Jong In Yook, Yong-Min Huh, Seungjoo Haam
Anchored Proteinase-Targetable Optomagnetic Nanoprobes for Molecular Imaging of Invasive Cancer Cells [Communication]
Activatable nanoprobe: A dual-function nanoprobe has been developed that detects membrane type 1-matrix metalloproteinase (MT1-MMP) activity by a dual-signal increase in complementary fluorescence imaging (FI) and magnetic resonance imaging (MRI). MNCs=magnetic nanocrystals, Q=quencher, F=fluorescence dye.
Nikola Ž. Knežević, Igor I. Slowing, Victor S.-Y. Lin
Tuning the Release of Anticancer Drugs from Magnetic Iron Oxide/Mesoporous Silica Core/Shell Nanoparticles [Full Paper]
A series of core/shell magnetic mesoporous silica nanoparticle (MMSN) materials were prepared. The loading and release of anticancer drugs, 9-aminoacridine (9AA) and camptothecin (CPT), as well as cytotoxic activity of drug loaded materials, is influenced by the presence of phenylethyl functionalization inside the MMSN mesopores (see figure). An externally applied magnetic field accelerates the drug release from the materials.
Xiao-Hui Guan, Bo-Tian Zheng, Min Lu, Xin Guan, Guang-Sheng Wang, Lin Guo
Highly Water-Dispersible Fe3O4 Single Nanocrystals: Gram-Scale Preparation by a Solution-Phase Route and Application for the Absorption of Cd2+ in Water [Full Paper]
It's all under control: High-yield production of Fe3O4 (10–15 nm) was realized by using a simple solution-phase method at room temperature. The Fe3O4 nanocrystals were continually synthesized by controlling the pH value of the reaction solution. The SEM, TEM, and XRD studies reveal the particles to be single nanocrystals. New adsorbents of FNBC are better at removing Cd2+ than BC and Fe3O4 nanocrystals.
Zhong Luo, Kaiyong Cai, Yan Hu, Jinghua Li, Xingwei Ding, Beilu Zhang, Dawei Xu, Weihu Yang, Peng Liu
Redox-Responsive Molecular Nanoreservoirs for Controlled Intracellular Anticancer Drug Delivery Based on Magnetic Nanoparticles [Communication]
Minoru Yamashita, Takasada Shibauchi, Yuji Matsuda
Thermal-Transport Studies on Two-Dimensional Quantum Spin Liquids [Minireview]
Gapped and gapless spin excitation, the latter having a long mean free path (ca. 1000 lattice distances), are revealed by thermal-transport studies on two organic insulators showing quantum spin liquid states, namely, κ-(BEDT-TTF)2Cu2(CN)3 and EtMe3Sb[Pd(dmit)2]2 (see picture), respectively. Such a long mean free path demonstrates remarkable coherence of the quantum condensed state. BEDT-TTF=bis(ethylenedithio)tetrathiafulvalene, dmit=1,3-dithiole-2-thione-4,5-dithiolate.
Mei Ding, Bingwu Wang, Zheming Wang, Junlong Zhang, Olaf Fuhr, Dieter Fenske, Song Gao
Constructing Single-Chain Magnets by Supramolecular π–π Stacking and Spin Canting: A Case Study on Manganese(III) Corroles [Full Paper]
Supramolecular magnets: Manganese(III) 5,10,15-tris(pentafluorophenyl)corrole [MnIII(tpfc)] forms chains or dimers depending on whether it was crystallized from methanol, ethyl acetate, or ethanol. Due to intermolecular π–π interactions, the depicted methanol solvate [Mn(tpfc)(MeOH)]·H2O forms a new type of supramolecular spin-canted single-chain magnet without any bridging ligands.
Haiquan Tian, Min Wang, Lang Zhao, Yun-Nan Guo, Yang Guo, Jinkui Tang, Zhiliang Liu
A Discrete Dysprosium Trigonal Prism Showing Single-Molecule Magnet Behaviour [Communication]
A magnetic personality: A unique dysprosium trigonal prism with a new polydentate Schiff-base ligand behaves as a single molecule magnet (SMM), which may stimulate further investigations into the relaxation dynamics of SMMs with different topologies (see figure).
Dawei Su, Josip Horvat, Paul Munroe, Hyojun Ahn, Ali R. Ranjbartoreh, Guoxiu Wang
Polyhedral Magnetite Nanocrystals with Multiple Facets: Facile Synthesis, Structural Modelling, Magnetic Properties and Application for High Capacity Lithium Storage [Full Paper]
Crystal class: Polyhedral magnetite nanocrystals were prepared by a low temperature hydrothermal method, in which multiple facets can be theoretically predicated (see figure). The as-prepared magnetite nanocrystals show a magnetic property of superspin glass state, and demonstrated an outstanding electrochemical performance for lithium storage in lithium ion cells.
Angela Datcu, Nans Roques, Véronique Jubera, Daniel Maspoch, Xavier Fontrodona, Klaus Wurst, Inhar Imaz, Georges Mouchaham, Jean-Pascal Sutter, Concepció Rovira, Jaume Veciana
Three-Dimensional Porous Metal–Radical Frameworks Based on Triphenylmethyl Radicals [Full Paper]
A rare find: MOFs that combine a fairly rare (6,3) connectivity and large 1D channels were obtained by reacting LnIII ions (Ln=Tb, Gd, Eu) with open- or closed-shell perchlorinated triphenylmethyl (PTM) ligands (see picture). Tb and Eu compounds based on the diamagnetic ligand show metal-centered luminescence. In radical-based complexes, {Ln-Radical; Ln=Tb, Gd} the interactions were found to be ferromagnetic.
Roberta Sessoli
Chilling with Magnetic Molecules [Highlight]
Fridge magnets: Molecular magnetism appears to be able to provide an alternative route for low-temperature refrigeration by providing molecules with large spin and weak magnetic anisotropy that display a large magnetocaloric effect.
Geert Dehaen, Svetlana V. Eliseeva, Kristof Kimpe, Sophie Laurent, Luce Vander Elst, Robert N. Muller, Wim Dehaen, Koen Binnemans, Tatjana N. Parac-Vogt
A Self-Assembled Complex with a Titanium(IV) Catecholate Core as a Potential Bimodal Contrast Agent [Full Paper]
Let's get photophysical: This work deals with the design and investigation of relaxometric and photophysical properties of a self-assembled supramolecular complex that contains three Ln-DTPA-catechol (DTPA=diethylenetriamine-N,N,N',N'',N''-pentaacetate) moieties around a central TiIV core (see figure).
Charles Lochenie, Wolfgang Bauer, Stephan Schlamp, Peter Thoma, Birgit Weber
Synthesis and Characterisation of Schiff Base-like Iron(II) Complexes with Imidazole as Axial Ligand [Article]
A. Rodríguez-Diéguez, José Manuel Seco, E. Colacio
[Co(μ-ox)(Hpmtz)] – A New CoII Zig-Zag Chain Complex with the In Situ Generated Oxalate Bridging and Hpmtz Chelating Ligands (Hpmtz = 5-pyrimidyltetrazole) Exhibiting Spin-Canted Antiferromagnetism [Short Communication]
![[Co(μ-ox)(Hpmtz)] – A New CoII Zig-Zag Chain Complex with the In Situ Generated Oxalate Bridging and Hpmtz Chelating Ligands (Hpmtz = 5-pyrimidyltetrazole) Exhibiting Spin-Canted Antiferromagnetism](http://www.wiley-vch.de/util/hottopics/img/ejic201101009.jpg "[Co(μ-ox)(Hpmtz)] – A New CoII Zig-Zag Chain Complex with the In Situ Generated Oxalate Bridging and Hpmtz Chelating Ligands (Hpmtz = 5-pyrimidyltetrazole) Exhibiting Spin-Canted Antiferromagnetism")
The neutral zig-zag oxalate bridged cobalt(II) chain complex [Co(μ-ox)(Hpmtz)] has been synthesized by hydrothermal techniques. Magnetic susceptibility measurements indicate that this compound shows a strong intrachain antiferromagnetic interaction and 3D weak ferromagnetic ordering at TC = 6.5 K.
Long Tang, Feng Fu, Loujun Gao, Yapan Wu, Qirui Liu, Xiaoming Gao
Erratum: A 3D Nickel(II) Coordination Polymer with cds Nets Constructed from 3-Pyridin-4-yl-benzoic Acid [Erratum]
Peter Jakes, Nina Blickhan, Tim Jekewitz, Alfons Drochner, Herbert Vogel, Hartmut Fuess, Rüdiger-A. Eichel
Interplay between Defect Structure and Catalytic Activity in the Mo10−xVxOy Mixed-Oxide System [Article]
Rationalize to catalyze: The Mo10−xVxOy solid-solution system (0≤x≤10) is studied by electron paramagnetic resonance spectroscopy. Concerning the catalytic activity of this system, the key role of the Mo/V ratio is revealed (see picture). Additionally a quantitative analysis of the [VO2+] concentration as a function of the Mo/V ratio allows one to characterize the prevailing defect chemistry.
Andrea Dei, Dante Gatteschi
Molecular (Nano) Magnets as Test Grounds of Quantum Mechanics [Essay]
A bitter pill? The dose of quantum concepts that chemists must digest is steadily increasing. The drug perhaps tastes bitter, but it produces good effects yielding novel systems to test the foundations of quantum mechanics. This point is considered in reference to molecular nanomagnets (see structure of a terbium phthalocyaninate complex), a class of materials that continues to show new facets requiring the exploration of new quantum effects.
H. S. Hsu, Y. Tung, Y. J. Chen, M. G. Chen, J. S. Lee, S. J. Sun
Defect engineering of room-temperature ferromagnetism of carbon-doped ZnO [Rapid Research Letter]
Room-temperature ferromagnetism observed in an air-annealed C:ZnO sample was associated with a ferromagnetic magnetic circular dichroism peak. This is related to the loss of carbon and the creation of defects in an air-annealed C:ZnO film by the reaction between carbon dopants and oxygen. In this Letter the authors suggest that a combination of carbon doping and a suitable post-annealing treatment has a strong impact on the defect-mediated ferromagnetism of C:ZnO.
M. Ziese
A spin-calorics device based on La0.7Sr0.3MnO3/SrRuO3 superlattices [Rapid Research Letter]
In this Letter a spin-caloric device is proposed that consists of a wedge-shaped La0.7Sr0.3MnO3/SrRuO3 superlattice (SL). Studies of SLs with various layer thicknesses show that the magnetic work can be strongly influenced by the engineering of the crystalline symmetry or the use of exchange biasing. A SL wedge in a rapidly varying magnetic field should therefore support a self-sustained Seebeck effect.
Alexander Makarov, Viktor Sverdlov, Dmitry Osintsev, Siegfried Selberherr
Reduction of switching time in pentalayer magnetic tunnel junctions with a composite-free layer [Rapid Research Letter]
In this Letter the authors report a substantial decrease of the switching time in a pentalayer structure with a composite-free layer as compared to the pentalayer structure of similar dimensions with a monolithic free layer. The physical reasons for the switching time reduction at the same current density are discussed.
S. M. Mohseni, S. R. Sani, J. Persson, T. N. Anh Nguyen, S. Chung, Ye. Pogoryelov, Johan Åkerman
High frequency operation of a spin-torque oscillator at low field [Rapid Research Letter]
In this Letter the authors demonstrate a nanocontact spin-torque oscillator (STO) based on an orthogonal spin-valve architecture with an in-plane Co polarizer and an out-of-plane Co/Ni multilayer free layer. High frequency operation at low external fields is achieved by tailoring the Co/Ni layer properties to increase the strength of the perpendicular magnetic anisotropy, while simultaneously reducing the saturation magnetization.
Michael Lorenz, Matthias Brandt, Katja Mexner, Kerstin Brachwitz, Michael Ziese, Pablo Esquinazi, Holger Hochmuth, Marius Grundmann
Ferrimagnetic ZnFe2O4 thin films on SrTiO3 single crystals with highly tunable electrical conductivity [Rapid Research Letter]
Within the current search for spintronic materials with spin polarized conductivity, zinc ferrite (ZnFe2O4) thin films grown on SrTiO3(001) and (111) single crystals are highly promising as magnetic semiconducting electrode in advanced all-oxide tunnel junctions and field effect transistors, as well as insulating barrier in spin filters. This is due to the highly tunable electrical conductivity coupled with high saturation magnetization.
Taiebeh Tahmasebi, Seidikkurippu N. Piramanayagam, Rachid Sbiaa, Hang Khume Tan, Randall Law, Sunny Lua, Tow Chong Chong
Tailoring the growth of L10-FePt for spintronics applications [Rapid Research Letter]
Ordered L10-FePt with large magnetocrystalline anisotropy (Ku) and high saturation magnetization (Ms) enables potential scaling of spintronic devices down to 5 nm. FePt films need to be smooth and possess good (001) texture in order to achieve the desired properties for spintronics applications. This Letter focuses on tailoring of L10-FePt growth for such applications. The L10-FePt magnetic layers deposited on Pd seed layers exhibit large ordering parameter, smoothness and strong perpendicular magnetic anisotropy.
C. Caspers, M. Müller, A. X. Gray, A. M. Kaiser, A. Gloskovskii, C. S. Fadley, W. Drube, C. M. Schneider
Electronic structure of EuO spin filter tunnel contacts directly on silicon [Rapid Research Letter]
Hard X-ray photoemission spectroscopy reveals the nearly ideal stoichiometry of EuO spin filter tunnel barriers grown directly on silicon, and the absence of silicon oxide formation at the EuO/Si interface. These results demonstrate the successful integration of a magnetic oxide tunnel barrier with silicon, paving the way for the future integration of magnetic oxides into functional spintronics devices.
R. Sbiaa, H. Meng, S. N. Piramanayagam
Materials with perpendicular magnetic anisotropy for magnetic random access memory [Review@RRL]
In this Review, the princple of spin-transfer torque magnetic random access memory (STT-MRAM) is explained: The magnetic tunnel junction device is sandwiched between two electrodes (cross-point architecture). The writing is based on spin torque effect and the reading on tunnelling magneto-resistive effect. In contrast to field-based MRAM, STT-MRAM does not require external magnetic field. Since STT-MRAM is scalable, the transistor scales down with the device size. Materials with perpendicular magnetic anisotropy (PMA) are being investigated for their use in STT-MRAM – multilayers such as Co/Pd and Co/Pt as well as FeCoB and future candidates such as FePt.
Sophie A. Morley, Nicholas A. Porter, Christopher H. Marrows
Magnetism and magnetotransport in sputtered Co-doped FeSi films [Rapid Research Letter]
Microelectronics manufacturing relies on planar processing for which thin films are needed. Sputtered films of cobalt-doped iron monosolicide have been fabricated and characterised. The non-centrosymmetric ε-phase is the predominant form of the material after annealing. It shows similar magnetic and magnetotransport properties to bulk single crystals in spite of the inherent disorder in a thin film. This includes a ratio of magnetic moment to carrier density of approximately unity, suggesting a high spin-polarisation in this silicon-based material.
Marcos Zayat, Rosario Pardo, Erick Castellón, Leonardo Torres, David Almendro, Pilar G. Parejo, Alberto Alvarez, Tomás Belenguer, Sara García-Revilla, Rolindes Balda, Joaquín Fernández, David Levy
Optical and Electro-optical Materials Prepared by the Sol-Gel Method [Research News]
The preparation and characterization of hybrid materials for optics and electro-optics via sol-gel methods is dicussed: hybrid coatings for smart-window applications, photoactive coatings, radiation-protection coatings, coatings for optical lenses and photochromic materials. The optical and electro-optical properties of the resulting materials are evaluated as potential components in photonic devices.
Inmaculada Alvarez-Serrano, Maria Angeles Arillo, Maria Luisa López, Maria Luisa Veiga, Carlos Pico
Tunable Ferrites as Environmentally Friendly Materials for Energy-Efficient Processes [Research News]
Spinel ferrites can be tuned for specifically highlighting their potential applications in magnetocaloric-refrigeration or lithium- battery technologies. Both the cation distribution in the octahedral and tetrahedral sites and the grain size are crucial factors that determine the magnetic and electrical responses. New methods are successfully employed to synthesize these ceramics with improved properties for specific applications.
Ravindranath Viswan, David Gray, Yaojin Wang, Yanxi Li, David Berry, Jiefang Li, D. Viehland
Strong magnetoelectric coupling in highly oriented ZnO films deposited on Metglas substrates [Rapid Research Letter]
In this Letter, the authors report the deposition of highly c-axis oriented ZnO films on Metglas substrates at a low temperature of 300 °C. A large converse magnetoelectric (CME) coefficient of about 3 × 10–6 s/m and a direct magnetoelectric (DME) coefficient of 47 mV/cm Oe were measured at a low dc magnetic field of 17 Oe and at a frequency of 1 kHz revealing a strong ME coupling in these layers.
Safa Golrokh Bahoosh, Steffen Trimper, Julia M. Wesselinowa
Origin of ferromagnetism in BaTiO3 nanoparticles [Rapid Research Letter]
Experimental observations show that nanocrystalline BaTiO3 offers ferromagnetism and a non-zero polarization at room-temperature. Within microscopic models we find the magnetization (red curve) and the polarization (blue curve) of the nanoparticles. The magnetic behaviour is due to the occurrence of Ti ions at the surface of the nanoparticles with nonzero spin. Below a critical size (characterized by the number of shells) the system reveals multiferroic behaviour.
Yaroslav Mudryk, Vitalij K. Pecharsky, Karl A. Gschneidner, Jr.
Extraordinary Responsive Intermetallic Compounds: the R5T4 Family (R = Rare Earth, T = Group 13–15 Element) [Research Report]
Donglu Shi, Nicholas M. Bedford, Hoon-Sung Cho
Engineered Multifunctional Nanocarriers for Cancer Diagnosis and Therapeutics [Review]
Carbon-based and/or magnetic nanocarriers—multifunctional nanomaterial systems—have received much attention in early cancer diagnosis and treatment. Advances in the design and development of such nanocarriers, including in-vivo studies, are reviewed in this article. Recommendations for future research are also given.
M. H. Chu, J. Segura-Ruiz, G. Martinez-Criado, P. Cloetens, I. Snigireva, S. Geburt, C. Ronning
Synchrotron fluorescence nanoimaging of a single Co-implanted ZnO nanowire [Rapid Research Letter]
Using a hard X-ray nanoprobe Chu, Segura-Ruiz and co-workers have investigated the elemental distribution in as-grown ZnO and Co implanted ZnO nanowires. Both Zn and Co elemental maps revealed a homogeneous distribution at the length scale of the X-ray beam size, without clustering or segregation effects. Within the nanoprobe spatial resolution, our findings indicate cobalt localization within thicker irregularities observed by scanning electron microscopy.
Maria A. Augustyniak-Jabłokow, Krzysztof Tadyszak, Mariusz Maćkowiak, Yurii V. Yablokov
EPR evidence of antiferromagnetic ordering in single-layer graphene [Rapid Research Letter]
This Letter presents the first experimental evidence of the theoretically predicted antiferromagnetic ordering in single layer graphene. A qualitative agreement with theory is obvious and the reasons of the quantitative differences are discussed. The obtained results prove that the electron paramagnetic resonance (EPR) is a powerful and effective tool for study of the magnetic properties of graphene.
Bernard Raveau, Valérie Pralong, Vincent Caignaert, Antoine Maignan
Swedenborgite-Type Cobaltites and Ferrites: Tetrahedral Frameworks with Exceptional Magnetic Properties [Research Report]
Yu. S. Dedkov, A. Generalov, E. N. Voloshina, M. Fonin
Structural and electronic properties of Fe3O4/graphene/Ni(111) junctions [Rapid Research Letter]
Graphene was recently proposed to be used as an effective spin-filtering material when sandwiched between two layers of ferromagnetic (FM) materials: Ni(111), Co(0001) or Fe(111)/Ni(111). However, the strong chemical interaction between the ferromagnetic film and graphene may destroy this effect. Replacement of one of the electrodes in the spin-filtering sandwich by a half-metallic ferromagnetic material, magnetite (Fe3O4), can help to overcome the main difficulties in the realization of such a device.
Richard Körmer, Michael Otto, Jia Wu, Michael P. M. Jank, Lothar Frey, Wolfgang Peukert
EPR investigations of non-oxidized silicon nanoparticles from thermal pyrolysis of silane [Rapid Research Letter]
This Letter reports electron paramagnetic resonance investigations on non-oxidized silicon nanoparticles (SiNP) from thermal silane pyrolysis. Increasing synthesis temperatures lead to higher dangling bond concentrations on the SiNP surface ascribed to an imperfect hydrogen termination. Native oxide formation or bromine addition leads to a decreasing dangling bond concentration, which demonstrates the high importance of the SiNP surface state.
Yaojin Wang, David Gray, David Berry, Junqi Gao, Jiefang Li, D. Viehland, Haosu Luo
Equivalent magnetic noise in magnetoelectric Metglas/Pb(Mg1/3Nb2/3)O3-PbTiO3 laminate composites [Rapid Research Letter]
The autors have studied the dominant internal noise sources of magnetoelectric laminate sensors. They theoretically estimated the values of the noise sources and experimentally confirmed these values. For longitudinally magnetized and thickness polarized mode (L-T mode) Metglas/PMN-PT sensors, the DC resistance noise dominates the equivalent magnetic noise at low frequencies, while the dielectric loss noise is the principal contribution above 2.5 Hz. Overall, the equivalent magnetic noise of the complete sensor unit was as small as 10.8 pT/Hz at f = 1 Hz.
Elena A. Rozhkova
Nanoscale Materials for Tackling Brain Cancer: Recent Progress and Outlook [Progress Report “Advanced Healthcare Materials”]
This article reports on recent progress in the development of advanced nanoscale photoreactive, magnetic and multifunctional materials applicable to brain cancer diagnostics, imaging, and therapy, with an emphasis on the latest contributions and the novelty of the approach, along with the most promising emergent trends.
Jens Müller
Fluctuation Spectroscopy: A New Approach for Studying Low-Dimensional Molecular Metals [Review]
Come on feel the noise: Fluctuation spectroscopy is described as a new tool to study the dynamics of charge carriers in organic conductors. In these materials the interplay of low dimensionality (see picture), strong electronic correlations and electron–lattice interactions give rise to a rich phenomenology of ground states. Intramolecular modes of lattice vibrations and the inhomogeneous coexistence region of antiferromagnetic (Mott) insulating and superconducting phases are discussed.
Thomas Traußnig, Stefan Topolovec, Kashif Nadeem, Dorothée Vinga Szabó, Heinz Krenn, Roland Würschum
Magnetization of Fe-oxide based nanocomposite tuned by surface charging [Rapid Research Letter]
In this Letter, the magnetization of a porous γ-Fe2O3–Pt nanocomposite is studied under the influence of charging the surfaces of the porous structure in an electrolyte. Reversible variations of the magnetization of up to 10.4% could be achieved upon charging. The present concept of tuning of magnetization may open up one promising niche path towards the current challenging efforts of controlling magnetism by electric fields.
D. V. Azamat, A. Dejneka, V. A. Trepakov, L. Jastrabik, M. Fanciulli, V. Y. Ivanov, M. Godlewski, V. I. Sokolov, J. Rosa, A. G. Badalyan
EPR spectroscopy of weak exchange interactions between Co2+ ions in ZnO [Rapid Research Letter]
Electron Paramagnetic Resonance (EPR) measurements have unambiguously shown the presence of exchanged-coupled Co2+ pairs in the heavily doped ZnO single crystals. This Letter reports on the first determination of the exchange tensor components of Co2+ dimers that are incorporated into the ZnO lattice in a highly selective way. The detailed EPR spectra are due to weakly ferromagnetically coupled next-nearest-neighbour Co2+ ions.
Jing Ma, Jiamian Hu, Zheng Li, Ce-Wen Nan
Recent Progress in Multiferroic Magnetoelectric Composites: from Bulk to Thin Films [Review]
Recent progress in multiferroic magnetoelectric composite systems such as bilayered magnetic-ferroelectric heterostructures where magnetic and ferroelectric orders coexist are reviewed. Strong magnetoelectric couplings across the magnetic-ferroelectric interface lead to magnetic (or electric)-field control of electric polarization (or magnetization), which promises new device applications such as sensors, transducer, oscillators, phase shifters, memory devices, and so on, controlled both electrically and magnetically.
Jian Liu, Shi Zhang Qiao, Qiu Hong Hu, Gao Qing (Max) Lu
Magnetic Nanocomposites with Mesoporous Structures: Synthesis and Applications [Review]
Magnetic nanocompsites with mesoporous structures, defined shapes, and tailored properties are of immense scientific and technological interest. This review highlights recent advances in the synthesis and applications of the nanocomposites of magnetic nanoparticles and mesoporous materials with different morphology and structures. In addition, some perspectives on the future developments and directions of the synthesis, device fabrication, and application of such magnetic particle and mesoporous material nanocomposites are provided.
Oliver Gutfleisch, Matthew A. Willard, Ekkes Brück, Christina H. Chen, S. G. Sankar, J. Ping Liu
Magnetic Materials and Devices for the 21st Century: Stronger, Lighter, and More Energy Efficient [Review]
A new energy paradigm, consisting of greater reliance on renewable energy sources and increased concern for energy efficiency, has accelerated research in energy-related technologies. Magnetic materials play an important role in improving the efficiency and performance of many devices. The impacts of hard magnets on electric motor and transportation technologies, of soft magnets on electricity generation and conversion technologies, and of magnetocaloric materials for refrigeration are discussed.
Emeline Souchier, Laurent Cario, Benoit Corraze, Philippe Moreau, Pascale Mazoyer, Claude Estournès, Richard Retoux, Etienne Janod, Marie-Paule Besland
First evidence of resistive switching in polycrystalline GaV4S8 thin layers [Rapid Research Letter]
This Letter reports on thin layers of GaV4S8 deposited by RF magnetron sputtering. The thin films (100–1000 μm) exhibit an electric pulse induced reversible resistive switching (RS) at 300 K: with writing/erasing times of ∼10 μs and switching ratio of >33%, in some cases even up to 200–300%. Using this original RS may be interesting for further RRAM (resistive RAM) applications.
K. Lawniczak-Jablonska, J. Libera, A. Wolska, M. T. Klepka, P. Dluzewski, J. Sadowski, D. Wasik, A. Twardowski, A. Kwiatkowski, K. Sato
The source of room temperature ferromagnetism in granular GaMnAs layers with zinc blende clusters [Rapid Research Letter]
The authors report new data on the cubic clusters formed in the MBE grown GaMnAs layer after thermal processing at 500 and 600 °C. Applying EXAFS technique they proved that in such clusters no hypothetic MnAs cubic structure was formed – but GaMnAs solid solutions with the content of Mn close to 20%, and this is sufficient to have ferromagnetic-like properties at room temperature.
Qingshan Wei, Alexander Wei
Optical Imaging with Dynamic Contrast Agents [Concept]
Finding needles in haystacks: Optical signals that are almost completely obscured by noisy environments can be elucidated by using dynamic contrast agents. Signals are modulated by stimuli-responsive molecules and nanoprobes, then demodulated to yield images with reduced backgrounds and enhanced optical contrast (see figure).
David C. Dunand, Peter Müllner
Size Effects on Magnetic Actuation in Ni-Mn-Ga Shape-Memory Alloys [Progress Report]
In Ni-Mn-Ga alloys the large twinning magnetic-field-induced strains (MFIS) present in monocrystals become negligible in polycrystals due to grain-boundaries constraints. When grain and sample sizes become comparable, constraints are relaxed and high MFIS become again possible. We review Ni-Mn-Ga powders, fibers, ribbons, and films where bamboo grains produce large MFIS, and “constructs” from these elements (mats, laminates, textiles, foams and composites).
Burkhard Luy
Towards Portable High-Resolution NMR Spectroscopy [Highlight]
Analysis on the go: Portable high-resolution NMR spectroscopy is of great interest for many applications. Recent advances in magnet design, spectrometer stability, and acquisition schemes have placed the realization of low-field spectrometers based on room-temperature permanent magnets and that can deliver chemical shift resolution within reach.
T. Harada, I. Ohkubo, M. Lippmaa, Y. Matsumoto, M. Sumiya, H. Koinuma, M. Oshima
Modulation of the ferromagnetic insulating phase in Pr0.8Ca0.2MnO3 by Co substitution [Rapid Research Letter]
It is important to clarify the origin of the ferromagnetic insulating phase in mixed-valent perovskites in order to design functional materials such as multiferroics. A detailed study given in this Letter on the effect of Co substitution on structural, magnetic, and transport properties of Pr0.8Ca0.2MnO3 revealed that the ferromagnetic insulating phase in Pr0.8Ca0.2Mn1–yCoyO3 originates from both double exchange and superexchange interactions which can be modulated by controlling the Mn/Co ratio in B-sites.
Elbert E. M. Chia, Jian-Xin Zhu, D. Talbayev, A. J. Taylor
Competing energy scales in high-temperature superconductors: Ultrafast pump–probe studies [Review@RRL]
The complex pucomplexesle of phases that can exist, co-exist, or compete in strongly correlated electron materials is among the greatest opportunities for progressing our understanding of solids state physics today. With this Review@RRL we are pleased to introduce an article category that, in line with the focus of pss (RRL), aims at highlighting most recent new developments in a particularly active field. Here the authors explain the insight that time-resolved spectroscopy brought for the study of photoexcited quasiparticle dynamics, discussing examples of cuprate and pnictide high-temperature superconductors in regimes where different phases such as superconductivity, spin-density-wave and pseudogap phases coexist or compete with one another.
© Wiley-VCH 2011.
RSS feed
