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We fabricate SrRuO3/PbZr0.52Ti0.48O3 heterostructures each with an in-plane tensile-strained SrRuO3 layer and investigate the effect of an applied electric field on anomalous Hall effect. The four-fold symmetry of anisotropic magnetoresistance and the nonmonotonic variation of anomalous Hall resistivity are observed. By applying positive electric field or negative electric field, the intersecting hump-like feature is suppressed or enhanced, respectively. The sign and magnitude of the anomalous Hall conductivity can be effectively controlled with an electric field under a high magnetic field. The electric-field-modulated anomalous Hall effect is associated with the magnetization rotation in SrRuO3. The experimental results are helpful in modulating the magnetization rotation in spintronic devices based on SrRuO3 heterostructures. [ABSTRACT FROM AUTHOR]

Electric field control of magnetism through nanoionics has attracted tremendous attention owing to its high efficiency and low power consumption. In solid-state dielectrics, an electric field drives the redistribution of ions to create one-dimensional magnetic conductive nanostructures, enabling the realization of intriguing magnetoresistance (MR) effects. Here, we explored the electric-controlled nickel and oxygen ion migration in Pt/HfO2− x /NiO y /Ni heterojunctions for MR modulation. By adjusting the voltage polarity and amplitude, the magnetic conductive filaments with mixed nickel and oxygen vacancy are constructed. This results in the reduction of device resistance by ∼103 folds, and leads to an intriguing partial asymmetric MR effect. We show that the difference of the device resistance under positive and negative saturation magnetic fields exhibits good linear dependence on the magnetic field angle, which can be used for magnetic field direction detection. Our study suggests the potential of electrically controlled ion migration in creating novel magnetic nanostructures for sensor applications. [ABSTRACT FROM AUTHOR]

In this study, it was investigated how the magnetic and electrical properties of the exchange biased multilayers are affected by the Pt and CuIr spacer layer thicknesses. For this purpose, CoFeB/NM/IrMn sample stacks which can be used as magnetic field sensors based on the anisotropic magnetoresistance and planar Hall effect (PHE) were designed. The magnetic and electrical results showed an unexpected behavior to the variations in the spacer layer thickness when a CuIr spacer layer was used instead of a Pt spacer layer in terms of the properties of exchange bias, anisotropic magneto-resistance voltage and PHE voltage. This phenomenon is explained by the layer interdiffusion between CuIr and IrMn layers. [ABSTRACT FROM AUTHOR]

High-quality Sr2CrWO6 (SCWO) films have been grown on SrTiO3 (STO) substrate by pulsed laser deposition under low oxygen pressure. With decrease of the film thickness, a drastic conductivity increase is observed. The Hall measurements show that the thicker the film, the lower the carrier density. An extrinsic mechanism of charge doping due to the dominance of oxygen vacancies at SCWO/STO interfaces is proposed. The distribution and gradient of carrier concentration in SCWO films are considered to be related to this phenomenon. Resistivity behavior observed in these films is found to follow the variable range hopping model. It is revealed that with increase of the film thickness, the extent of disorder in the lattice increases, which gives a clear evidence of disorder-induced localization charge carriers in these films. Magnetoresistance measurements show that there is a negative magnetoresistance in SCWO films, which is considered to be caused by the magnetic scattering of magnetic elements Cr3+ and W5+. In addition, a sign reversal of anisotropic magnetoresistance (AMR) in SCWO film is observed for the first time, when the temperature varies across a characteristic value, T M. Magnetizationâ€"temperature measurements demonstrate that this AMR sign reversal is caused by the direction transition of easy axis of magnetization from the in-plane ferromagnetic order at T > T M to the out-of-plane at T < T M. [ABSTRACT FROM AUTHOR]

Anisotropic magnetoresistance (AMR) and related planar Hall resistance (PHR) are ubiquitous phenomena of magnetic materials. Although the universal angular dependences of AMR and PHR in magnetic polycrystalline materials with one order parameter are well known, no similar universal relation for other class of magnetic materials are known to date. Here a general theory of galvanomagnetic effects in magnetic materials is presented with two vector order parameters, such as magnetic single crystals with a dominated crystalline axis or polycrystalline non-collinear ferrimagnetic materials. It is shown that AMR and PHR have a universal angular dependence. In general, both longitudinal and transverse resistivity are non-reciprocal in the absence of inversion symmetry: Resistivity takes different values when the current is reversed. Different from simple magnetic polycrystalline materials where AMR and PHR have the same magnitude, and π /4 out of phase, the magnitudes of AMR and PHR of materials with two vector order parameters are not the same in general, and the phase difference is not π /4. Instead of π periodicity of the usual AMR and PHR, the periodicities of materials with two order parameters are 2 π. [ABSTRACT FROM AUTHOR]

We demonstrate a method to dope monolayer chemical vapor deposited (CVD) graphene with nitrogen and make it ferromagnetic. CVD graphene was first functionalized with hydroxyl groups by treating with H2O2 in the presence of UV light and then annealed in ammonia gas to dope it with nitrogen. Magnetization measurements showed a ferromagnetic hysteresis loop at low temperatures with a coercivity of 222 Oe at 2 K. We also investigated the effect of a change in the angle of the applied magnetic field on the anisotropic magnetoresistance effect (AMR) in the doped CVD graphene devices. Graphene shows positive AMR for temperatures from 2 K to 50 K, negative AMR at 100 K and 150 K, and no AMR for temperatures higher than 150 K. A maximum AMR of 0.92% was observed at 2 K for an in-plane magnetic field of 30 kOe. Magnetic force microscopy also confirms the introduction of magnetism in CVD graphene after doping, and electron spin resonance spectroscopy shows resonance when scanned in a magnetic field, which confirms the presence of unpaired electrons in doped graphene. The process introduced in this paper for nitrogen doping of graphene with attendant magnetism could pave the way for the applications of graphene in spintronics and other devices. [ABSTRACT FROM AUTHOR]

Cobalt thin films have been grown by plasma-enhanced atomic layer deposition using bis(cyclopentadienyl)cobalt(II) as cobalt precursor and NH3 plasma as a reducing agent. Electric and magnetic properties are investigated as a function of the growth temperature. A transition from a regime of temperature independent film thickness to a thermally-activated growth is observed at 340 °C. In the self-limited growth regime, magnetization increases and resistivity decreases with temperature. On the contrary, in the thermally-activated regime, magnetization decreases and resistivity increases with temperature. This results in an optimal growth temperature of 340 °C at which the magnetization equals bulk cobalt and the resistivity is 14 µΩ cm. Rotating magnetic field measurements show a magnetoresistance of 1.1% at room temperature ascribed to conventional anisotropic magnetoresistance. This study shows that magnetoresistive properties of cobalt thin films grown by atomic layer deposition are comparable to those obtained by physical vapor deposition and reveals that atomic layer deposition might be an alternative deposition technique for ferromagnetic layers in the field of spintronics. [ABSTRACT FROM AUTHOR]

We report the observation of in-plane anisotropic magnetoresistance and planar Hall effect in non-magnetic HfTe5 thin layers. The observed anisotropic magnetoresistance as well as its sign is strongly dependent on the critical resistivity anomaly temperature Tp. Below Tp, the anisotropic magnetoresistance is negative with large negative magnetoresistance. When the in-plane magnetic field is perpendicular to the current, the negative longitudinal magnetoresistance reaches its maximum. The negative longitudinal magnetoresistance effect in HfTe5 thin layers is dramatically different from that induced by the chiral anomaly as observed in Weyl and Dirac semimetals. One potential underlying origin may be attributed to the reduced spin scattering, which arises from the in-plane magnetic field driven coupling between the top and bottom surface states. Our findings provide valuable insights for the anisotropic magnetoresistance effect in topological electronic systems and the device potential of HfTe5 in spintronics and quantum sensing. [ABSTRACT FROM AUTHOR]

The Weyl semimetal has emerged as a new topologically nontrivial phase of matter, hosting low-energy excitations of massless Weyl fermions. Here, we present a comprehensive study of a type-II Weyl semimetal WP2. Transport studies show a butterfly-like magnetoresistance at low temperature, reflecting the anisotropy of the electron Fermi surfaces. This four-lobed feature gradually evolves into a two-lobed variant with an increase in temperature, mainly due to the reduced relative contribution of electron Fermi surfaces compared to hole Fermi surfaces for magnetoresistance. Moreover, an angle-dependent Berry phase is also discovered, based on quantum oscillations, which is ascribed to the effective manipulation of extremal Fermi orbits by the magnetic field to feel nearby topological singularities in the momentum space. The revealed topological character and anisotropic Fermi surfaces of the WP2 substantially enrich the physical properties of Weyl semimetals, and show great promises in terms of potential topological electronic and Fermitronic device applications. [ABSTRACT FROM AUTHOR]

The angular dependence of the microwave-driven spin rectification (SR) effect in single crystalline Co0.5Fe0.5 alloy film is systematically investigated. Due to the strong current-orientation dependent anisotropic magnetoresistance (AMR), the SR effects in CoFe film strongly deviate from the ordinary sin 2φM cos φM relation with φM defined as the magnetization angle away from the current. A giant Gilbert damping anisotropy in the CoFe film with a maximum–minimum ratio of 520% is observed, which can impose a strong anisotropy onto magnetic susceptibility. The observed unusual angular dependence can be well explained by the theory including current-orientation dependent AMR and anisotropic magnetic susceptibility. Our work also suggests that the strong current-orientation dependent AMR in single crystalline CoFe film could exist up to the gigahertz frequency range. [ABSTRACT FROM AUTHOR]

The Weyl semimetal has emerged as a new topologically nontrivial phase of matter, hosting low-energy excitations of massless Weyl fermions. Here, we present a comprehensive study of a type-II Weyl semimetal WP2. Transport studies show a butterfly-like magnetoresistance at low temperature, reflecting the anisotropy of the electron Fermi surfaces. This four-lobed feature gradually evolves into a two-lobed variant with an increase in temperature, mainly due to the reduced relative contribution of electron Fermi surfaces compared to hole Fermi surfaces for magnetoresistance. Moreover, an angle-dependent Berry phase is also discovered, based on quantum oscillations, which is ascribed to the effective manipulation of extremal Fermi orbits by the magnetic field to feel nearby topological singularities in the momentum space. The revealed topological character and anisotropic Fermi surfaces of the WP2 substantially enrich the physical properties of Weyl semimetals, and show great promises in terms of potential topological electronic and Fermitronic device applications. [ABSTRACT FROM AUTHOR]

We study the reversal mechanisms in a self-assembled, hexagonally ordered Fe antidot array with a period of 200 nm and an antidot diameter of 100 nm which was prepared by polystyrene nanosphere lithography. Direction-dependent information in such a self-assembled sample is obtained by measuring the anisotropic magnetoresistance (AMR) through constrictions processed by focused ion beam milling in nearest neighbor and next nearest neighbor directions. We show that such an originally integral method can be used to investigate the strong in-plane anisotropy introduced by the antidot lattice. The easy and hard axis reversal mechanisms and corresponding AMR signals are modeled by micromagnetic simulations. Additional in-field magnetic force microscopy studies allow the correlation of microscopic switching to features in the integral AMR. We find that the easy axis of magnetization is connected to a distinct periodic magnetic domain pattern, which can be observed during the whole magnetization reversal. While this process is driven by nucleation and propagation of reversed domains, the hard axis reversal is characterized by a (stepwise) rotation of the magnetization via the antidot lattice’ easy axes. [ABSTRACT FROM AUTHOR]

Field-direction dependence of Hall resistance and anisotropic magnetoresistivity has been systematically investigated in a perpendicularly exchange-coupled [Pt/Co]/IrMn system. We combine the results of anomalous Hall effect and planar Hall effect to describe the process of magnetization reversal at all field angles. These measurements provide strong evidence that the Hall resistance is closely related to different field directions in the normal plane as well as in the film plane, revealing the sensitivity of the signals to the field direction even when it is slightly deviated from the film plane. These observed correlations between electrical properties and magnetization in the perpendicular exchange coupling system would not only help to understand the spin alignments of an exchange-coupled magnet, but also propose a possible magnetic sensor for full space detection, opening a promising avenue to detect a wide range of magnetic fields at all angles. [ABSTRACT FROM AUTHOR]

We review colossal magnetoresistance in single phase manganites, as related to the field sensitive spin-charge interactions and phase separation; the rectifying property and negative/positive magnetoresistance in manganite/Nb:SrTiO3 p—n junctions in relation to the special interface electronic structure; magnetoelectric coupling in manganite/ferroelectric structures that takes advantage of strain, carrier density, and magnetic field sensitivity; tunneling magnetoresistance in tunnel junctions with dielectric, ferroelectric, and organic semiconductor spacers using the fully spin polarized nature of manganites; and the effect of particle size on magnetic properties in manganite nanoparticles. [ABSTRACT FROM AUTHOR]

Recent advances in the study of exchange couplings in magnetic films are introduced. To provide a comprehensive understanding of exchange coupling, we have designed different bilayers, trilayers and multilayers, such as anisotropic hard- /soft-magnetic multilayer films, ferromagnetic/antiferromagnetic/ferromagnetic trilayers, [Pt/Co]/NiFe/NiO heterostructures, Co/NiO and Co/NiO/Fe trilayers on an anodic aluminum oxide (AAO) template. The exchange-coupling interaction between soft- and hard-magnetic phases, interlayer and interfacial exchange couplings and magnetic and magnetotransport properties in these magnetic films have been investigated in detail by adjusting the magnetic anisotropy of ferromagnetic layers and by changing the thickness of the spacer layer, ferromagnetic layer, and antiferromagnetic layer. Some particular physical phenomena have been observed and explained. [ABSTRACT FROM AUTHOR]

The ferromagnetic semi-conductive Cr2Ge2Te6 with van der Waals bonded layers is prominent for characteristics of easy exfoliation and tunablility, which make it a potential candidate for spintronic application. Although the magnetism has been investigated intensively, the transport property is rarely studied, which is very important for the realization of its application. In this work, the electronic transport of Cr2Ge2Te6 is investigated under external magnetic field with variable directions. The angle-dependent resistance shows absolute isotropic property in the ab-plane. However, it displays anisotropic characteristic when the magnetic field is rotated from the ab-plane to the c-axis. The resistance reaches the maximum when H//c while it is the minimum when H//ab. Moreover, the field-dependent resistance of Cr2Ge2Te6 shows a positive magnetoresistance (MR) effect when H//c but a negative one when H//ab. We suggest that the anisotropic MR behaviors of Cr2Ge2Te6 can be understood theoretically within the framework based on the exchange interaction between the carriers and local magnetic moments. [ABSTRACT FROM AUTHOR]

Magneto-optic Kerr effect (MOKE) microscopy involves the surface-sensitive probing of magnetisation at micron-sized lateral resolution. Here, we present a low-temperature, focused polar MOKE microscope for simultaneous magneto-optic and magneto-transport measurements which has a temperature range of 1.6–300 K and is equipped with a magnet capable of delivering a field of up to 9 T. In this microscope, all optical components are integrated in a free-standing probe, allowing for straightforward incorporation into many non-optical cryostat systems. Two-dimensional magnetisation scans on patterned ferromagnetic [CoFeB/Pt]n films demonstrate a magnetisation sensitivity of 10 µrad (Kerr angle) and a spatial resolution of 2.2 µm. The combination of optical and electrical measurements provides complementary temperature-dependent information, as demonstrated by the study of magnetic topological insulator thin films with out-of-plane magnetic anisotropy. Using this complementary approach, we study the effects of a secondary phase in Cr and V co-doped Sb2Te3 thin films, which show a combination of weak antilocalisation and anisotropic magnetoresistance effects above 70 K. Our results highlight the virtue of MOKE and electrical transport to optimise exotic topological magnetic materials, paving the way for energy-efficient spintronic devices. [ABSTRACT FROM AUTHOR]

We demonstrate anisotropic resistivity measurements using the extended van der Pauw (vdP) method in ferromagnetic Ni80Fe20 (Py) films. We apply it to measure anisotropic magnetoresistance (AMR) and compare the results of the vdP method with the more conventional Hall-bar method along the hard and easy axis of the film and show that the vdP method gives more reliable AMR result. For instance the AMR result along the hard and easy axis of the film are in close agreement. Further, we applied the vdP method to study AMR in a series of Py films with thicknesses ranging between 10–250 nm. The films were grown by sputtering deposition at an angle with respect to the substrate normal and with an in situ magnetic field, both conditions assisting in the definition of in-plane uniaxial anisotropy. The microstructure of Py films was characterized using x-ray reflectivity, diffraction and polar mapping of (1 1 1) planes. We detected no off-normal texture and negligible surface roughness, which indicates that self-shadowing is not dominating in our growth. Yet the films have well defined uniaxial anisotropy. Abrupt changes in the average resistivity versus film thickness were observed, which cannot be explained by the models accounting for the thickness and grain size but strongly correlate with the changes in (1 1 1) texture in the films. We compared our results with the literature and show that independent of growth method, substrate and deposition temperature, the AMR value presents a saturation behavior with thickness at about 100 nm. [ABSTRACT FROM AUTHOR]

Revealing the physical nature of vortex wall (VW) behavior in magnetic nanostructures has been of great importance for future device concepts. Here we introduce the superior properties of VW in a notched FeNi nanowire under the action of an electronic current. The pinning-dependent VW propagation is demonstrated by a successive in-field magnetic force microscopy, an anisotropic magnetoresistance measurement, as well as micromagnetics. Based on the developed method, the propagation of VW can be effectively captured by monitoring the change of magnetoresistance in the FeNi nanowire, which sheds light on the development of future spin-based devices. [ABSTRACT FROM AUTHOR]

Particle acceleration in space and astrophysical reconnection sites is an important unsolved problem in studies of magnetic reconnection. Earlier kinetic simulations have identified several acceleration mechanisms that are associated with particle drift motions. Here, we show that, for sufficiently large systems, the energization processes due to particle drift motions can be described as fluid compression and shear, and that the shear energization is proportional to the pressure anisotropy of energetic particles. By analyzing results from fully kinetic simulations, we show that the compression energization dominates the acceleration of high-energy particles in reconnection with a weak guide field, and the compression and shear effects are comparable when the guide field is 50% of the reconnecting component. Spatial distributions of those energization effects reveal that reconnection exhausts, contracting islands, and island-merging regions are the three most important regions for compression and shear acceleration. This study connects particle energization by particle guiding-center drift motions with that due to background fluid motions, as in the energetic particle transport theory. It provides foundations for building particle transport models for large-scale reconnection acceleration such as those in solar flares. [ABSTRACT FROM AUTHOR]

We investigate the thermal entanglement of the spin-1 Ising–Heisenberg diamond chain, which can be regarded as a theoretical model for the homometallic molecular ferrimagnet . Two cases, i.e., the isotropic Heisenberg (Ising–XXX) coupling model and anisotropic Heisenberg (Ising–XXZ) coupling model, are discussed respectively. The negativity is chosen as the measurement of the thermal entanglement. By means of the transfer-matrix approach, we focus on the effects of biquadratic interaction parameters on the negativity of the infinite spin-1 Ising–Heisenberg diamond chain. In the Ising–XXX coupling model, it is shown that for the case with ferromagnetic coupling the thermal entanglement can be induced by the biquadratic interaction, but the external magnetic field will suppress the occurrence of the entanglement induced by the biquadratic interaction. In the Ising–XXZ coupling model, for the case with antiferromagnetic coupling, due to the biquadratic interaction the effect of the anisotropy parameter on the entanglement will be suppressed at near-zero temperature. Moreover, the biquadratic interaction makes the threshold temperature increase. The effects of the external magnetic field on the thermal entanglement are also discussed, and it is observed that the entanglement revival phenomena exist in both models considered. [ABSTRACT FROM AUTHOR]

Dynamic myocardial perfusion computed tomography (MPCT) is a promising technique for quick diagnosis and risk stratification of coronary artery disease. However, one major drawback of dynamic MPCT imaging is the heavy radiation dose to patients due to its dynamic image acquisition protocol. In this work, to address this issue, we present a robust dynamic MPCT deconvolution algorithm via adaptive-weighted tensor total variation (AwTTV) regularization for accurate residue function estimation with low-mA s data acquisitions. For simplicity, the presented method is termed ‘MPD-AwTTV’. More specifically, the gains of the AwTTV regularization over the original tensor total variation regularization are from the anisotropic edge property of the sequential MPCT images. To minimize the associative objective function we propose an efficient iterative optimization strategy with fast convergence rate in the framework of an iterative shrinkage/thresholding algorithm. We validate and evaluate the presented algorithm using both digital XCAT phantom and preclinical porcine data. The preliminary experimental results have demonstrated that the presented MPD-AwTTV deconvolution algorithm can achieve remarkable gains in noise-induced artifact suppression, edge detail preservation, and accurate flow-scaled residue function and MPHM estimation as compared with the other existing deconvolution algorithms in digital phantom studies, and similar gains can be obtained in the porcine data experiment. [ABSTRACT FROM AUTHOR]

Laboratory measurements are used to constrain the dielectric tensor for graphite, from microwave to X-ray frequencies. The dielectric tensor is strongly anisotropic even at X-ray energies. The discrete dipole approximation is employed for accurate calculations of absorption and scattering by single-crystal graphite spheres and spheroids. For randomly oriented single-crystal grains, the so-called approximation for calculating absorption and scattering cross sections is exact in the limit and provides better than ∼10% accuracy in the optical and UV even when is not small, but becomes increasingly inaccurate at infrared wavelengths, with errors as large as ∼40% at . For turbostratic graphite grains, the Bruggeman and Maxwell Garnett treatments yield similar cross sections in the optical and ultraviolet, but diverge in the infrared, with predicted cross sections differing by over an order of magnitude in the far-infrared. It is argued that the Maxwell Garnett estimate is likely to be more realistic, and is recommended. The out-of-plane lattice resonance of graphite near 11.5 μm may be observable in absorption with the MIRI spectrograph on James Webb Space Telescope. Aligned graphite grains, if present in the interstellar medium, could produce polarized X-ray absorption and polarized X-ray scattering near the carbon K edge. [ABSTRACT FROM AUTHOR]

In this paper, we propose a polarization beam splitter utilizing an ultra-thin anisotropic metasurface. The proposed anisotropic element is composed of triple-layered rectangular patches spaced with double-layered dielectric isolators. By tailoring the metallic patches, the cell is capable of transmitting x-polarized waves efficiently and reflecting y-polarized beams with almost 100% efficiency at 15 GHz. In addition to this, the reflected phases can be modulated by adjusting the size of the element, which contributes to beam steering in reflection mode. By assigning gradient phases on the metasurface, the constructed sample has the ability to refract x-polarized waves normally and reflect y-polarized beams anomalously. For verification, a sample with a size of 240 240 mm2 is fabricated and measured. Consistent numerical and experimental results have both validated the efficiently anomalous reflection for y-polarized waves and normal refraction for x-polarized beams operating from 14.6–15.4 GHz. Furthermore, the proposed sample has a thickness of 0.1λ at 15 GHz, which provides a promising approach for steering and splitting beams in a compact size. [ABSTRACT FROM AUTHOR]

In this paper we introduce invariance under anisotropic transformations to cosmology. This invariance is one of the key ingredients of the theory of quantum gravity at a Lifshitz point put forward by Hořava. We find that this new symmetry in the minisuperspace introduces characteristics to the model that can be relevant in the ultraviolet regime. For example, by canonical quantization we find a Schrödinger-type equation which avoids the problem of frozen time in quantum cosmology. For simple cases we obtain solutions to this quantum equation in a Kantowski–Sachs (KS) minisuperspace. At the classical level, we study KS and Friedmann–Robertson–Walker cosmologies, obtaining modifications to the solutions of general relativity that can be relevant in the early Universe. [ABSTRACT FROM AUTHOR]

We study the behaviour of Bianchi class A universes containing an ultra-stiff isotropic ghost field and a fluid with anisotropic pressures which is also ultra-stiff on the average. This allows us to investigate whether cyclic universe scenarios, like the ekpyrotic model, do indeed lead to isotropization on approach to a singularity (or bounce) in the presence of dominant ultra-stiff pressure anisotropies. We specialize to consider the closed Bianchi type IX universe, and show that when the anisotropic pressures are stiffer on average than any isotropic ultra-stiff fluid then, if they dominate on approach to the singularity, it will be anisotropic. We include an isotropic ultra-stiff ghost fluid with negative energy density in order to create a cosmological bounce at finite volume in the absence of the anisotropic fluid. When the dominant anisotropic fluid is present it leads to an anisotropic cosmological singularity rather than an isotropic bounce. The inclusion of anisotropic stresses generated by collisionless particles in an anisotropically expanding universe is therefore essential for a full analysis of the consequences of a cosmological bounce or singularity in cyclic universes. [ABSTRACT FROM AUTHOR]

Using in situ electric-field-modulated anisotropic magnetoresistance measurement, a large reversible and nonvolatile in-plane rotation of magnetic easy axis of ∼35° between the positive and negative electrical poling states is demonstrated in Co40Fe40B20/(001)-cut Pb(Mg1/3Nb2/3)O3-0.25PbTiO3 (PMN-PT). The specific magnetoelectric coupling mechanism therein is experimentally verified to be related to the synchronous in-plane strain rotation induced by 109° ferroelastic domain switching in the (001)-cut PMN-PT substrate. [ABSTRACT FROM AUTHOR]

Multicluster models consider that the nucleons can be moving around different centers in the nuclei. These models have been widely used to describe light nuclei but always considering that the mean field is composed of isotropic harmonic oscillators with different centers. In this work, we propose an extension of these models by using anisotropic harmonic oscillators. The strengths of these oscillators, the distance among the different centers and the disposition of the nucleons inside every cluster are free parameters which have been fixed using the variational criterion. All the one-body and two-body matrix elements have been analytically calculated. Only a numerical integration on the Euler angles is needed to carry out the projection on the values of the total spin of the state and its third component. We have studied the ground state and the first excited states of 8Be, 12C and 10Be getting good results for the energies. The disposition of the nucleons in the different clusters have also been analyzed by using projection on the different Cartesian planes getting much more information than when the radial one-body density is used. [ABSTRACT FROM AUTHOR]

Mn2Au is one of the few candidate materials for antiferromagnetic spintronics requiring ordered metals with a high Néel-temperature and strong spin–orbit coupling. We report the preparation of epitaxial Mn2Au thin films by rf-sputtering. Structural characterization by x-ray and electron diffraction demonstrates a high degree of atomic order and the temperature dependence of the resistivity is typical for a good metal. The magnetic properties of the samples are studied by the investigation of Mn2Au/Fe bilayers. Exchange bias effects are observed, which present strong evidence for antiferromagnetic order in the Mn2Au thin films. Small domains of 500 nm are visualized in the exchange coupled Fe thin film. [ABSTRACT FROM AUTHOR]

A phenomenological quantization of electromagnetic field is introduced in the presence of the anisotropic magnetodielectric metamaterial. For a single layer structure with the anisotropic metamaterial, input–output relations of quantized radiation are derived using the Green-function approach. Based on these relations, the reflectance of the linearly polarized wave through this structure is calculated. The results show that different resonant peaks of reflectance appear for different polarized waves and indicate the use of the anisotropic metamaterial as a reflector for a certain polarized wave. Furthermore it is found that such a structure can realize the resonant gap with the increase of the thickness. Finally the effects of the absorption are considered and we find that the above properties do not change with the introduction of the absorption. [ABSTRACT FROM AUTHOR]

Recently the planar version of the extraordinary magnetoresistance (EMR) magnetic field sensor has been constructed and verified in practice. Planar configuration of the EMR device gives many technological advantages, it is simpler than the classic and allows one to build the sensor using electric materials of the new type (such as graphene or topological insulators) much easier. In this work the planar configuration of the EMR sensor is investigated by performing computational simulations using the finite element method (FEM). The computational comparison of the planar and classic configurations of EMR is presented using three-dimensional models. Various variants of the geometry of EMR sensor components are pondered and compared in the planar and classic version. Size of the metal overlap is considered for sensor optimization as well as various semiconductor-metal contact resistance dependences of the EMR signal. Based on computational simulations, a method for optimal placement of electric terminals in a planar EMR device is proposed. [ABSTRACT FROM AUTHOR]

We demonstrate single atom anisotropic magnetoresistance on the surface of a topological insulator, arising from the interplay between the helical spin–momentum-locked surface electronic structure and the hybridization of the magnetic adatom states. Our first-principles quantum transport calculations based on density functional theory for Mn on Bi2Se3 elucidate the underlying mechanism. We complement our findings with a two dimensional model valid for both single adatoms and magnetic clusters, which leads to a proposed device setup for experimental realization. Our results provide an explanation for the conflicting scattering experiments on magnetic adatoms on topological insulator surfaces, and reveal the real space spin texture around the magnetic impurity. [ABSTRACT FROM AUTHOR]

We use the Schwinger-boson approach to study the anisotropy ferrimagnetic spin-(1/2,1) chain with bond alternation. Based on the effect of bond alternation δ, we obtain energy gap, free energy, and specific heat, respectively. The specific heat with larger bond alternation (δ > 0.7) displays a peak at low temperature. Based on the effect of XXZ anisotropy parameter Δ, we present excited spectrums, free energy, and specific heat, respectively. [ABSTRACT FROM AUTHOR]

Recent advances in technology have enabled the combination of positron emission tomography (PET) with magnetic resonance imaging (MRI). These PET-MRI scanners simultaneously acquire functional PET and anatomical or functional MRI data. As function and anatomy are not independent of one another the images to be reconstructed are likely to have shared structures. We aim to exploit this inherent structural similarity by reconstructing from both modalities in a joint reconstruction framework. The structural similarity between two modalities can be modelled in two different ways: edges are more likely to be at similar positions and/or to have similar orientations. We analyse the diffusion process generated by minimizing priors that encapsulate these different models. It turns out that the class of parallel level set priors always corresponds to anisotropic diffusion which is sometimes forward and sometimes backward diffusion. We perform numerical experiments where we jointly reconstruct from blurred Radon data with Poisson noise (PET) and under-sampled Fourier data with Gaussian noise (MRI). Our results show that both modalities benefit from each other in areas of shared edge information. The joint reconstructions have less artefacts and sharper edges compared to separate reconstructions and the ℓ2-error can be reduced in all of the considered cases of under-sampling. [ABSTRACT FROM AUTHOR]

A correction to the article "Anisotropic bonded magnets fabricated via surfactant-assisted ball milling and magnetic-field processing" that was published in the December 10, 2012 issue is presented.

Six-fold anisotropic magnetoresistance (AMR) was observed in epitaxial Fe3O4(1 1 1) films on conductive ZnO (0 0 0 1), while the current flowed perpendicularly to the film plane and the magnetic field rotated in the film plane, demonstrating the close relation between AMR and magnetocrystalline anisotropy. The spin injection efficiency of Fe3O4 films was modulated from 60% to 20% with increasing underlayer ZnO surface roughness through changing the sputtering pressure. Larger AMR is observed in epitaxial Fe3O4(1 1 1) films with higher spin injection efficiency. Under the induction of a magnetic field and magnetocrystalline anisotropic fields along the easy axis, it is supposed that the scattering of carriers by the noncollinear moments near antiphase boundaries is weaker for the films with higher spin injection efficiency. [ABSTRACT FROM AUTHOR]