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The electrical outputs of single-layer antiferromagnetic memory devices relying on the anisotropic magnetoresistance effect are typically rather small at room temperature. Here we report a new type of antiferromagnetic memory based on the spin phase change in a Mn-Ir binary intermetallic thin film at a composition within the phase boundary between its collinear and noncollinear phases. Via a small piezoelectric strain, the spin structure of this composition-boundary metal is reversibly interconverted, leading to a large nonvolatile room-temperature resistance modulation that is two orders of magnitude greater than the anisotropic magnetoresistance effect for a metal, mimicking the well-established phase change memory from a quantum spin degree of freedom. In addition, this antiferromagnetic spin phase change memory exhibits remarkable time and temperature stabilities, and is robust in a magnetic field high up to 60 T. Antiferromagnets have a variety of attractive features such as rapid operation, lack of stray fields, and insensitivity to external perturbations, that make an exciting prospect for memory and computing applications. Unfortunately, readout of the antiferromagnetic state is challenging. Here, Yan, Mao and coauthors demonstrate an antiferromagnet that can be switched between antiferromagnetic phases via piezoelectric strain with a large difference in the resistance between the two antiferromagnetic phases. [ABSTRACT FROM AUTHOR]

A EuZnSb2 antiferromagnetic (AFM) semi metal with a P4/nmm space group (No. 129) is synthesized using the Sb-flux method. The magnetic properties, specific heat, and resistivity of the EuZnSb2 single crystals are analyzed. The magnetic and specific heat properties indicate an antiferromagnetic order of Eu2+ with TN ~ 20 K. The magnetic field is observed to suppress the AFM transition of Eu2+ and the magnetic susceptibility vs. temperature curves exhibit differences when the magnetic field is applied along the ab-plane and c-axis of EuZnSb2 single crystal, reflecting a weak in-plane anisotropy of Eu2+. When the temperature is below 20 K, a spin‒flop transition of the AFM order appears at approximately 1.6 T. The electronic transport measurements indicate that a EuZnSb2 single crystal exhibits metallic properties and an extremely unsaturated positive MR effect. A twofold period of anisotropic magnetoresistance is observed, indicating that the resistivity characteristics correlate with the magnetic field intensity and the angle between the magnetic field direction and the crystallographic axis direction. These studies contribute to enriching the magnetic, specific thermal, and electrical transport properties of EuZnSb2. These results also provide valuable information for further research on other AFM materials. [ABSTRACT FROM AUTHOR]

A EuZnSb2 antiferromagnetic (AFM) semi metal with a P4/nmm space group (No. 129) is synthesized using the Sb-flux method. The magnetic properties, specific heat, and resistivity of the EuZnSb2 single crystals are analyzed. The magnetic and specific heat properties indicate an antiferromagnetic order of Eu2+ with TN ~ 20 K. The magnetic field is observed to suppress the AFM transition of Eu2+ and the magnetic susceptibility vs. temperature curves exhibit differences when the magnetic field is applied along the ab-plane and c-axis of EuZnSb2 single crystal, reflecting a weak in-plane anisotropy of Eu2+. When the temperature is below 20 K, a spin‒flop transition of the AFM order appears at approximately 1.6 T. The electronic transport measurements indicate that a EuZnSb2 single crystal exhibits metallic properties and an extremely unsaturated positive MR effect. A twofold period of anisotropic magnetoresistance is observed, indicating that the resistivity characteristics correlate with the magnetic field intensity and the angle between the magnetic field direction and the crystallographic axis direction. These studies contribute to enriching the magnetic, specific thermal, and electrical transport properties of EuZnSb2. These results also provide valuable information for further research on other AFM materials. [ABSTRACT FROM AUTHOR]

Magnetic field-induced changes in the electrical resistance of materials reveal insights into the fundamental properties governing their electronic and magnetic behavior. Various classes of magnetoresistance have been realized, including giant, colossal, and extraordinary magnetoresistance, each with distinct physical origins. In recent years, extreme magnetoresistance (XMR) has been observed in topological and non-topological materials displaying a non-saturating magnetoresistance reaching 103−108% in magnetic fields up to 60 T. XMR is often intimately linked to a gapless band structure with steep bands and charge compensation. Here, we show that a linear XMR of 80,000% at 15 T and 2 K emerges at the high-mobility interface between the large band-gap oxides γ-Al2O3 and SrTiO3. Despite the chemically and electronically very dissimilar environment, the temperature/field phase diagrams of γ-Al2O3/SrTiO3 bear a striking resemblance to XMR semimetals. By comparing magnetotransport, microscopic current imaging, and momentum-resolved band structures, we conclude that the XMR in γ-Al2O3/SrTiO3 is not strongly linked to the band structure, but arises from weak disorder enforcing a squeezed guiding center motion of electrons. We also present a dynamic XMR self-enhancement through an autonomous redistribution of quasi-mobile oxygen vacancies. Our findings shed new light on XMR and introduce tunability using dynamic defect engineering. Extreme magnetoresistance is characterized by a large and non-saturating magnetoresistance. Typically, it is observed in materials with compensated bandstructures, however, here, Christensen et al demonstrate a large and non-saturating magnetoresistance in a γAl2O3/SrTiO3 heterostructure, which is related to disorder, rather than the materials bandstructure. [ABSTRACT FROM AUTHOR]

Achieving room-temperature high anisotropic magnetoresistance ratios is highly desirable for magnetic sensors with scaled supply voltages and high sensitivities. However, the ratios in heterojunction-free thin films are currently limited to only a few percent at room temperature. Here, we observe a high anisotropic magnetoresistance ratio of −39% and a giant planar Hall effect (520 μΩ⋅cm) at room temperature under 9 T in β-Ag2Te crystals grown by chemical vapor deposition. We propose a theoretical model of anisotropic scattering — induced by a Dirac cone tilt and modulated by intrinsic properties of effective mass and sound velocity — as a possible origin. Moreover, small-size angle sensors with a Wheatstone bridge configuration were fabricated using the synthesized β-Ag2Te crystals. The sensors exhibited high output response (240 mV/V), high angle sensitivity (4.2 mV/V/°) and small angle error (<1°). Our work translates the developments in topological insulators to a broader impact on practical applications such as high-field magnetic and angle sensors. Achieving room-temperature high anisotropic magnetoresistance ratios is highly desirable for magnetic sensors. Here, the authors observe a high anisotropic magnetoresistance ratio of −39% and a giant planar Hall effect (520 μΩ·cm) at room temperature under 9 T in β-Ag2Te crystals grown by CVD. [ABSTRACT FROM AUTHOR]

Temperature and magnetic field–dependent electrical and magnetic properties of La1−xCaxMnO3 (x = 0.4, 0.5) polycrystalline materials prepared by the sol-gel method are studied. An apically compressed/elongated-type distorted orthorhombic pnma-O′–phase crystallization occurs in the sample with the addition of Ca. The crystallized phases are ensured by the Rietveld refinement using the Fullprof package. Dangling bonds on the surfaces of the nanosized particles affect the vibrational features. Field emission scanning electron microscopy (FESEM) images depict the agglomeration of uniformly sized grains. With increase of Ca concentration, super-exchange (SE) interactions overcome the dominant double-exchange (DE) interactions and shift the Curie-temperature to a lower value (TC = 267 – 234K). Based on the Banerjee's criterion, the Arrott plot confirms a second-order magnetic phase transition in the samples. Temperature-dependent evolution of the Griffiths-like phase (GP) is observed in the samples and GP% increases with Ca content. The various transitions in the different temperature ranges and magnetic field–dependent electrical transport behaviours are explained using different theoretical models. The dopant concentration influences the Mn3+/Mn4+ ratio, leading to changes in the conductivity, which is mediated by ferromagnetically (FM) ordered conduction channels, altering the metal to insulator (M-I) as well as the ferromagnetic to paramagnetic (FM-PM) as well as the ferromagnetic to antiferromagnetic (FM-AFM) transition temperatures. The electrical transport in the high temperature region is explained using variable range and small polaron hopping (VRH and SPH) models. Using Holstein's relation, it is evident that non-adiabatic SPH (NASPH) model is the most adequate method to explain the high-temperature electrical conductivity. The half-doped samples show a higher value (~ 95%) of magnetoresistance (MR). The present study shows an increase in the Tc and TM − I towards room temperature and in the MR percentage, which may be good for different applications. [ABSTRACT FROM AUTHOR]

The confluence between high-energy physics and condensed matter has produced groundbreaking results via unexpected connections between the two traditionally disparate areas. In this work, we elucidate additional connectivity between high-energy and condensed matter physics by examining the interplay between spin-orbit interactions and local symmetry-breaking magnetic order in the magnetotransport of thin-film magnetic semimetal FeRh. We show that the change in sign of the normalized longitudinal magnetoresistance observed as a function of increasing in-plane magnetic field results from changes in the Fermi surface morphology. We demonstrate that the geometric distortions in the Fermi surface morphology are more clearly understood via the presence of pseudogravitational fields in the low-energy theory. The pseudogravitational connection provides additional insights into the origins of a ubiquitous phenomenon observed in many common magnetic materials and points to an alternative methodology for understanding phenomena in locally-ordered materials with strong spin-orbit interactions. There are areas where high-energy and condensed-matter physics can successfully overlap a prominent example being topological matter and the role of supersymmetry. Here, via anisotropic magnetoresistance, the authors investigate distortions in the Fermi surface geometry of FeRh films and provide a theoretical interpretation that considers the results within the framework of a pseudogravitational fields. [ABSTRACT FROM AUTHOR]

The ExoMars programme has the objective to answer to the question of whether life ever existed on Mars. The second mission comprising the Rosalind Franklin rover and Kazachok Surface Platform was designed to focus specifically on the characterization of the environmental parameters which can play an important role for the existence of life on the surface of the planet. One of these parameters is the magnetic field because of its ability of shielding the solar and cosmic radiation. For such characterization, the scientific suite of the Surface Platform counts with two instruments: the Anisotropic MagnetoResistance (AMR) and the MArtIan Ground ElectromagneTic (MAIGRET) instruments. The AMR goal is to characterize both the surface and subsurface and the time-varying magnetic fields, related to the crustal and the external fields respectively, at the ExoMars landing site in Oxia Planum. The operation to achieve these goals includes two phases, the first phase corresponding to the lander descent and the second phase in which the instrument is deployed on the surface. In this work, we simulate the first operations phase using synthetic magnetic field models, assuming that the different crustal units at the landing site might be magnetized. We also perform measurements in our laboratory to simulate the second phase operation of the instrument on the Martian surface. We discuss the capability of interpretation of the instrument, based on the available information of the landing site and the results from our models. [ABSTRACT FROM AUTHOR]

Discovering and understanding anomalous anisotropic magnetoresistance (AMR) effects are important aspects of studying the nature of modulated transport. The anisotropic transport coefficients of topological systems are often useful for mapping hidden phases and characterizing topological phase transitions and the evolution of topological electrons. Here, we report an unusual change in the AMR effect in HoPtBi. Remarkably, the AMR exhibits transitions from a quasi-twofold to fourfold symmetry and finally forms a stable rotated fourfold symmetry with increasing magnetic fields. The evolution analysis from the three-dimensional (3D) mapping experiments confirms that it is an intrinsic 3D effect. Fourier transformation analysis indicates that the superposition of C2, C4, and C6 signals with phase angle transitions leads to the novel AMR. All transitions are summarized as symmetry rotation or the inversion of peaks and valleys. By combining the features of band structures and AMR, we evaluate the possible origin of this symmetry rotation and attribute it to the topological band change. This work provides insight into the anomalous AMR effect of topological materials and is useful for understanding the evolution of topological bands in a magnetic field. We propose that other rare-earth half-Heusler alloys can potentially exhibit similar phenomena. Topological semimetal HoPtBi exhibits anomalous AMR effect in paramagnetic state. The AMR exhibits a novel transition from a quasi-twofold to fourfold symmetry and finally forms a stable rotated fourfold symmetry as B increases. C2 and C4 signals with phase angle transitions dominate the novel AMR. Anisotropy of magnetic-field tunable effect induces the topological band change and leads to the phase angle transition. [ABSTRACT FROM AUTHOR]

The influence of magnetocrystalline anisotropy in antiferromagnets is evident in a spin flip or flop transition. Contrary to spin flops, a spin-flip transition has been scarcely presented due to its specific condition of relatively strong magnetocrystalline anisotropy and the role of spin-flips on anisotropic phenomena has not been investigated in detail. In this study, we present antiferromagnet-based functional properties on an itinerant Ising antiferromagnet Ca0.9Sr0.1Co2As2. In the presence of a rotating magnetic field, anomalous Hall conductivity and anisotropic magnetoresistance are demonstrated, the effects of which are maximized above the spin-flip transition. Moreover, a joint experimental and theoretical study is conducted to provide an efficient tool to identify various spin states, which can be useful in spin-processing functionalities. [ABSTRACT FROM AUTHOR]

The ultra-thin heterostructure of Pr0.6Sr0.4MnO3(15 nm)/Pr0.5Ca0.5MnO3(15 nm)/SrTiO3 fabricated using pulsed laser deposition technique exhibits the phase-segregated nature wherein the ferromagnetism of Pr0.6Sr0.4MnO3, and the antiferromagnetic state of Pr0.5Ca0.5MnO3 coexist in proximity. The observation of two exciting phenomena in the grown ultra-thin heterostructure, namely, the kinetic arrest and training effect, confirms its phase-segregated nature. The melting of the antiferromagnetic state in Pr0.5Ca0.5MnO3 into a ferromagnetic state due to the interfacial interaction arising from the magnetic proximity of the ferromagnetic clusters of Pr0.6Sr0.4MnO3 have been observed. A metal–insulator transition (TMIT) found at 215 K, close to its Curie temperature (TCurie) observed at 230 K, reveals a strong correlation between the electrical transport and the magnetization of the ultra-thin heterostructure. The electrical conduction in the high-temperature regime is explained in terms of the adiabatic small polaron hopping model. While the resistance in the metallic regime for temperatures above 100 K is contributed by the inelastic scattering due to the two-magnons, in the metallic regime below 100 K, the one-magnon inelastic scattering contribution is prevalent. An enhanced colossal magnetoresistance property near room temperature is obtained in the ultra-thin heterostructure arising from the proximity-driven interfacial interaction, making it a suitable candidate for technological applications near room temperature. [ABSTRACT FROM AUTHOR]

The ultra-thin heterostructure of Pr0.6Sr0.4MnO3(15 nm)/Pr0.5Ca0.5MnO3(15 nm)/SrTiO3 fabricated using pulsed laser deposition technique exhibits the phase-segregated nature wherein the ferromagnetism of Pr0.6Sr0.4MnO3, and the antiferromagnetic state of Pr0.5Ca0.5MnO3 coexist in proximity. The observation of two exciting phenomena in the grown ultra-thin heterostructure, namely, the kinetic arrest and training effect, confirms its phase-segregated nature. The melting of the antiferromagnetic state in Pr0.5Ca0.5MnO3 into a ferromagnetic state due to the interfacial interaction arising from the magnetic proximity of the ferromagnetic clusters of Pr0.6Sr0.4MnO3 have been observed. A metal–insulator transition (TMIT) found at 215 K, close to its Curie temperature (TCurie) observed at 230 K, reveals a strong correlation between the electrical transport and the magnetization of the ultra-thin heterostructure. The electrical conduction in the high-temperature regime is explained in terms of the adiabatic small polaron hopping model. While the resistance in the metallic regime for temperatures above 100 K is contributed by the inelastic scattering due to the two-magnons, in the metallic regime below 100 K, the one-magnon inelastic scattering contribution is prevalent. An enhanced colossal magnetoresistance property near room temperature is obtained in the ultra-thin heterostructure arising from the proximity-driven interfacial interaction, making it a suitable candidate for technological applications near room temperature. [ABSTRACT FROM AUTHOR]

The observation of magnetoresistance (MR) varying with the rotation of magnetization in the plane perpendicular to the electric current is an important discovery in spintronics in recent years. The famous conventional anisotropic MR (AMR) says that the resistance of a polycrystalline magnetic material must depend on magnetization component along the current direction only, thus cannot account for this newly observed unusual AMR (UAMR). This UAMR leads to the notion of the spin-Hall MR (SMR) in the famous SMR theory. However, the SMR theory may only explain UAMR observed in heavy-metal/magnetic-insulator bilayers, not other types of bilayers. Here, we present a two-vector theory that can explain not only all existing experiments on the unusual angular dependence of longitudinal and transverse resistivity when the magnetization rotates in three mutually perpendicular planes, but also how three amplitudes of MR angular oscillation are related to each other. The theory is very general and its correctness depends only on the assumption that the magnetization and interfacial field are the only vectors affecting electron transport besides of other scalar variables such as the temperatures and impurities. Experiments that can test this theory against the SMR theory are also proposed. [ABSTRACT FROM AUTHOR]

Van der Waals heterostructures offer great versatility to tailor unique interactions at the atomically flat interfaces between dissimilar layered materials and induce novel physical phenomena. By bringing monolayer 1 T' WTe2, a two-dimensional quantum spin Hall insulator, and few-layer Cr2Ge2Te6, an insulating ferromagnet, into close proximity in an heterostructure, we introduce a ferromagnetic order in the former via the interfacial exchange interaction. The ferromagnetism in WTe2 manifests in the anomalous Nernst effect, anomalous Hall effect as well as anisotropic magnetoresistance effect. Using local electrodes, we identify separate transport contributions from the metallic edge and insulating bulk. When driven by an AC current, the second harmonic voltage responses closely resemble the anomalous Nernst responses to AC temperature gradient generated by nonlocal heater, which appear as nonreciprocal signals with respect to the induced magnetization orientation. Our results from different electrodes reveal spin-polarized edge states in the magnetized quantum spin Hall insulator. Van der Waals heterostructures allow for the integration of several materials with different properties in the one heterostructure. Here, Li et al combine a quantum spin hall insulator, WTe2, with an insulating ferromagnet, Cr2Ge2Te6, in a van der Waals heterostructure, with resulting proximity-induced magnetism in the WTe2 layer leading to an anomalous Hall and Nernst effect. [ABSTRACT FROM AUTHOR]

In the last decade, nanoscale resistive devices with memory have been the subject of intense study because of their possible use in brain-inspired computing. However, operational endurance is one of the limiting factors in the adoption of such technology. For this reason, we discuss the emergence of current-induced memristance in magnetic materials, known for their durability. We show analytically and numerically that a single ferromagnetic layer can possess GHz memristance, due to a combination of two factors: a current-induced transfer of angular momentum (Zhang-Li torque) and the anisotropic magnetoresistance (AMR). We term the resulting effect the anisotropic magneto-memristance (AMM). We connect the AMM to the topology of the magnetization state, within a simple model of a one-dimensional annulus-shaped magnetic layer, confirming the analytical results with micromagnetic simulations for permalloy. Our results open a new path towards the realization of single-layer magnetic memristive devices operating at GHz frequencies. Memristors are reconfigurable devices that are switchable between low and high resistive states and are expected to play an important role in the integrated circuit technology of next generation computing. Here, the authors theoretically demonstrate that ring-shaped nanostructures composed of a ferromagnetic material can exhibit memristive properties with performance values in the GHz range. [ABSTRACT FROM AUTHOR]

Magnetic sensors are widely used in our daily life for assessing the position and orientation of objects. Recently, the magnetic sensing modality has been introduced to electronic skins (e-skins), enabling remote perception of moving objects. However, the integration density of magnetic sensors is limited and the vector properties of the magnetic field cannot be fully explored since the sensors can only perceive field components in one or two dimensions. Here, we report an approach to fabricate high-density integrated active matrix magnetic sensor with three-dimensional (3D) magnetic vector field sensing capability. The 3D magnetic sensor is composed of an array of self-assembled micro-origami cubic architectures with biased anisotropic magnetoresistance (AMR) sensors manufactured in a wafer-scale process. Integrating the 3D magnetic sensors into an e-skin with embedded magnetic hairs enables real-time multidirectional tactile perception. We demonstrate a versatile approach for the fabrication of active matrix integrated 3D sensor arrays using micro-origami and pave the way for new electronic devices relying on the autonomous rearrangement of functional elements in space. State-of-the-art magnetic skins can only sense in one or two-dimensions, at small spatial resolutions. By combining the ancient art of paper folding, origami, with advanced semiconductor technology, here, authors present cutting edge three-dimensional magnetic sensors. [ABSTRACT FROM AUTHOR]

The major challenges in the commercialization of spintronic devices lie in the high-dimensional materials with low spin-current generation efficiency and expensive fabrication processes. Recent discovery on the magnetoresistance (MR) phenomenon of graphene nanosheets could suggest that graphene-based materials can be excellent materials for spintronic devices. To develop two-dimensional materials with high MR at the low magnetic field and room temperature, we design and develop hybrid graphene nanosheets by using the matrix-assisted pulsed laser evaporation (MAPLE) technique. FeCo nanoparticles (NPs) are deposited onto the reduced graphene oxide (rGO) nanosheets in a stoichiometric manner by the MAPLE process. The density and size of FeCo NPs on rGO can be simply adjusted by varying the deposition time (t). Most importantly, with a limited FeCo ratio (0.4 at.%), MAPLE-prepared FeCo/rGO hybrid nanosheets display an MR phenomenon (MR up to 0.7%) at the low magnetic field (10 kOe) and room temperature. In this paper, we demonstrate that the MAPLE process can be used to produce hybrid graphene nanosheets with MR properties. The results of this work can contribute to the development of spintronic devices, e.g., ultra-thin MR sensors. [ABSTRACT FROM AUTHOR]

Low-dimensional nano and two-dimensional materials are of great interest to many disciplines and may have a lot of applications in fields such as electronics, optoelectronics, and photonics. One can create quantum Hall phases by applying a strong magnetic field perpendicular to a two-dimensional electron system. One characterizes the nature of the system by looking at magneto-transport data. There have been a few quantum phases seen in past experiments on GaAs/AlGaAs heterostructures that manifest anisotropic magnetoresistance, typically, in high Landau levels. In this work, we model the source of anisotropy as originating from an internal anisotropic interaction between electrons. We use this framework to study the possible anisotropic behavior of finite clusters of electrons at filling factor 1/6 of the lowest Landau level. [ABSTRACT FROM AUTHOR]

With an ever intensifying hunt for quantum materials with integrated functionalities, transition metal oxides provide a simple yet rich option to explore. In this article, we bring out the potential of a perovskite oxide KTaO3 (KTO) as a candidate for future generation quantum technologies as well as a hunting ground to understand the topological effects in oxides. We show that the heterostructures of insulating KTO with other insulating oxides LaVO3 (LVO) and EuO are not only conducting, but have strong spin-orbit coupling leading to momentum-dependent spin-splitting—the Rashba effect. In LVO–KTO, the Rashba spin-split bands are shown to give rise to anisotropic magnetoresistance and planar Hall effect, while in EuO–KTO, a non-trivial Berry's phase analysed from the quantum Shubnikov-de Haas oscillations is observed. [ABSTRACT FROM AUTHOR]

With an ever intensifying hunt for quantum materials with integrated functionalities, transition metal oxides provide a simple yet rich option to explore. In this article, we bring out the potential of a perovskite oxide KTaO3 (KTO) as a candidate for future generation quantum technologies as well as a hunting ground to understand the topological effects in oxides. We show that the heterostructures of insulating KTO with other insulating oxides LaVO3 (LVO) and EuO are not only conducting, but have strong spin-orbit coupling leading to momentum-dependent spin-splitting—the Rashba effect. In LVO–KTO, the Rashba spin-split bands are shown to give rise to anisotropic magnetoresistance and planar Hall effect, while in EuO–KTO, a non-trivial Berry's phase analysed from the quantum Shubnikov-de Haas oscillations is observed. [ABSTRACT FROM AUTHOR]

Sputtered Tb/Cr/Fe structures with a Cr layer (tCr) thickness ranging from 0 to 4 nm were prepared. The coercivity (Hc) of Tb/Cr (tCr)/Fe films with tCr ≥ 1 nm is consistent with that of the corresponding Cr(tCr)/Fe films. At the same time, the addition of the Tb layer results in a large saturation magnetization field (Hs) and even oscillatory relations of Hs on tCr, which might indicate an oscillatory indirect exchange coupling mediated by the spin polarization of the spacer Cr layer. Consistent oscillations are observed in anisotropic magnetoresistance (AMR) originating in spin–orbit coupling and magnetoresistance (MR) associated with interlayer exchange coupling as tCr in Tb/Cr/Fe films increases. The oscillatory MR demonstrates antiferromagnetic coupling, which also implies that it is not ordinary MR, although it is of the same magnitude as a result of the nonsharp interfaces. The value of the antiferromagnetic exchange coupling J as a function of tCr is estimated. Consistent oscillations with those in MR and AMR versus tCr are found, accompanied by a gradually flattened oscillation for films with tCr ≥ 2.5 nm resulting from weak coupling as the thick spacer Cr layer. Compared with the curves of MR, AMR, and J versus tCr, the opposite oscillations observed in the curve of Hc/Hs versus tCr further confirm the oscillatory interlayer exchange coupling in the studied structure, which provides theoretical basis for the adjustment of magnetic properties in spintronics by rare earth elements. [ABSTRACT FROM AUTHOR]

Previous studies have shown that Rashba-Edelstein effect may exist at the permalloy (Py)/Al2O3 interface due to inversion symmetry breaking. We systematically investigated the magnetoresistance and spin-torque ferromagnetic resonance (ST-FMR) in a series of Py/δPt/Al2O3 structures, where the Py/Al2O3 interface is decorated with or without ultra-thin Pt. The magnetoresistance measurements show that the original Py/Al2O3 exhibits an ordinary anisotropic magnetoresistance, while Pt decoration introduces an additional spin–orbit magnetoresistance. The ST-FMR measurements show that a damping-like torque does exist in Py/Al2O3 but are relatively small compared with the Pt decorated samples, and the previously observed field-like torque in Py/Al2O3 may be contributed mainly by the Oersted field caused by the current inhomogeneity. Our results suggest that the strength of spin–orbit coupling at the Py/Al2O3 interface is relatively weak and can be enhanced by Pt decoration. [ABSTRACT FROM AUTHOR]

Realizing applicably appreciated spintronic functionalities basing on the coupling between charge and spin degrees of freedom is still a challenge. For example, the anisotropic magnetoresistance (AMR) effect can be utilized to read out the information stored in magnetic structures. However, the application of AMR in antiferromagnet-based spintronics is usually hindered by the small AMR value. Here, we discover a colossal AMR with its value reaching 1.84 × 106% at 2 K, which stems from the field-induced metal-to-insulator transition (MIT), in a nearly Dirac material EuMnSb2. Density functional theory calculations identify a Dirac-like band around the Y point that depends strongly on the spin–orbit coupling and dominates the electrical transport. The indirect band gap at the Fermi level evolves with magnetic structure of Eu2+ moments, consequently giving rise to the field-induced MIT and the colossal AMR. Our results suggest that the antiferromagnetic topological materials can serve as a fertile ground for spintronics applications. [ABSTRACT FROM AUTHOR]

Electrical conduction in magnetic materials depends on their magnetization configuration, resulting in various magnetoresistances (MRs). The microscopic mechanisms of MR have so far been attributed to either an intrinsic or extrinsic origin, yet the contribution and temperature dependence of either origin has remained elusive due to experimental limitations. In this study, we independently probed the intrinsic and extrinsic contributions to the anisotropic MR (AMR) of a permalloy film at varying temperatures using temperature-variable terahertz time-domain spectroscopy. The AMR induced by the scattering-independent intrinsic origin was observed to be approximately 1.5% at T = 16 K and is virtually independent of temperature. In contrast, the AMR induced by the scattering-dependent extrinsic contribution was approximately 3% at T = 16 K but decreased to 1.5% at T = 155 K, which is the maximum temperature at which the AMR can be resolved using THz measurements. Our results experimentally quantify the temperature-dependent intrinsic and extrinsic contributions to AMR, which can stimulate further theoretical research to aid the fundamental understanding of AMR. [ABSTRACT FROM AUTHOR]

Double perovskite La2−xSrxMnRuO6 (x = 0, 0.3, 0.5, 0.8, 1.0) samples were synthesized by the standard solid-state reaction method. The compounds can be well indexed as an orthorhombic structure with the space group of Pnma at room temperature. The Sr-doped samples exhibit a stronger ferromagnetic behavior than the undoped sample, which is responsible for the ferromagnetic super-exchange interaction of Mn3+-O2−-Ru4+. The Curie temperature of all samples increases with the increasing Sr2+ concentration. All the samples show a semiconducting-like behavior, and the nature of electrical conduction can be well described by Mott's three-dimensional variable range hopping model. The appropriate Sr2+ substitution can effectively enhance the magnetoresistance effect. An enhanced negative magnetoresistance effect (~ 49%) in the La1.5Sr0.5MnRuO6 sample was observed at 25 K and 7 T. [ABSTRACT FROM AUTHOR]

Size and heat treatment effects in magnetoresistive properties of Ag-added Ni80Fe20 film systems prepared by the method of electron-beam co-evaporation at room temperature were investigated. For all as-deposited samples, the isotropic magnetoresistance, which value increase with the growth of sample thickness within the range from 20 to 100 nm, was observed. The maximum magnetoresistance was observed for Ag-added Ni80Fe20 film systems with a total thickness of 60 nm annealed to 500 K. The high-temperature annealing to 700 K leads to a decrease in the value of magnetoresistance and appearing of the anisotropic magnetoresistive effect. Magnetic investigations of thin films allow indicating that nanosized permalloy grains have ferromagnetic nature and conditional the isotropic behavior of magnetoresistance in as-deposited samples. [ABSTRACT FROM AUTHOR]

Printed electronics are attractive due to their low-cost and large-area processing features, which have been successfully extended to magnetoresistive sensors and devices. Here, we introduce and characterize a new kind of magnetoresistive paste based on the anisotropic magnetoresistive (AMR) effect. The paste is a composite of 100-nm-thick permalloy/tantalum flakes embedded in an elastomer matrix, which promotes the formation of appropriately conductive percolation networks. Sensors printed with this paste showed stable magnetoresistive properties upon mechanical bending. The AMR value of this sensor is 0.34 % in the field of 400 mT. Still, the response is stable and allows to resolve sub-mT field steps. When printed on ultra-thin 2.5- μ m -thick Mylar foil, the sensor can be completely folded without losing magnetoresistive performance and mechanically withstand 20 μ m bending radius. The developed compliant printed AMR sensor would be attractive to implement on curved and/or dynamic bendable surfaces for on-skin applications and interactive printed electronics. [ABSTRACT FROM AUTHOR]

The present work shows the comprehensive investigations of phase state, magnetic properties, magnetoresistive, and magnetocaloric effects of AlCrFeCoNiCu thin-film high-entropy alloy (HEA). Mosaic target with six segments has been used for tailoring the film composition. The results show that the magnetic and magnetoresistive properties of HEA thin films are significantly affected by the presence of the face-centered-cubic (FCC) phase, which is formed during the annealing process. High-defective structure of thin films in as-deposited state results in the presence of the paramagnetic phase causing the absence of spontaneous magnetization and magnetoresistance. The formation of the FCC phase during heat treatment leads to the anisotropic magnetoresistance appearance. Besides, the low values of coercivity and magnetization at 300 K of annealed thin films point out that these samples could be potentially useful for the magnetocaloric application due to the compositional tunability. [ABSTRACT FROM AUTHOR]

The magnetic and magnetoresistance properties of anisotropic magnetoresistance (AMR) sensors based on Wheatstone bridge (WB) with barber pole and conventional Hall bar structures were studied. The samples were prepared by using standard microlithography and sputter deposition techniques and then measured by magneto-optic Kerr effect and magneto transport methods. The advantages of the AMR sensor based on WB compared with Hall bar structure were discussed. It was observed that sensitivity was increased almost 15 times when sensors with the WB structures were used instead of Hall bar structures. Moreover, sensor stability was tested in various external magnetic fields with positive and negative polarities. The test results show that sensor response is stable even in various external magnetic fields up to 5000 Oe. The changes in sensitivity and output voltage were attributed to WB structure. [ABSTRACT FROM AUTHOR]

The structural, magnetic, electrical, and thermoelectric behaviors of lanthanum silver manganite and lanthanum bismuth silver manganite were thoroughly studied in the present work. Two polycrystalline samples, viz., La0.835Ag0.165MnO3 (LAMO) and La0.67Bi0.165Ag0.165MnO3 (LBAMO) possessing almost constant ratio of Mn3+/Mn4+ were synthesized using the wet chemical method. Phase formation was identified from powder X-ray diffraction and it has been confirmed through the structural analysis of which samples crystallize into rhombohedral symmetry with R-3C space group. Apparent changes at phase transition temperature were observed in temperature-dependent resistivity, magnetization and thermoelectric power behavior for bismuth-doped samples. In addition, an enhanced magnetoresistance was observed in LBAMO samples and is attributed to the presence of both ferromagnetic and anti-ferromagnetic states. The temperature-dependent resistivity data in the temperature range (50–300 K) were analyzed using the phase separation model. Spin-dependent scattering and electron–electron interactions were considered to explain the resistivity minimum in the low temperature region (T < 50 K). The Seebeck coefficient is positive and enhances around the transition temperature by substituting bismuth into LAMO. The high-temperature thermoelectric power data were explained in the framework of small polaron hopping mechanism while magnon drag effect dominates in the low temperature region. [ABSTRACT FROM AUTHOR]

Antiferromagnets have attracted considerable interest in the field of spintronics due to their attractive characteristics such as ultrafast spin dynamics and robustness against external magnetic field perturbations. Sr2IrO4 is a rare example of antiferromagnetic semiconductor oxide and has been extensively studied in anisotropic magnetoresistance-based spintronics. However, the anisotropic magnetoresistance of Sr2IrO4 films is usually very small. Herein, we have prepared a (Sr2IrO4)4/(La2/3Sr1/3MnO3)5 superlattice which shows an enhanced anisotropic magnetoresistance compared to Sr2IrO4 film or La2/3Sr1/3MnO3/Sr2IrO4 heterostructure and an obvious nonvolatile memory effect that is comparable to Sr2IrO4 single crystals. Through magnetic measurements, the increased coercivity and the exchange bias at low temperatures reveal the interfacial magnetic coupling between Sr2IrO4 and La2/3Sr1/3MnO3. Additionally, the remarkable anisotropic magnetoresistance and clear hysteresis of anisotropic magnetoresistance with distinct fourfold symmetry can be controlled by temperature and magnetic field. These findings demonstrate that the superlattices of heavy transition metal oxide Sr2IrO4 are excellent platforms for antiferromagnetic spintronics. [ABSTRACT FROM AUTHOR]

Among the perovskite oxide family, KTaO3 (KTO) has recently attracted considerable interest as a possible system for the realization of the Rashba effect. In this work, we report a novel conducting interface by placing KTO with another insulator, LaVO3 (LVO) and report planar Hall effect (PHE) and anisotropic magnetoresistance (AMR) measurements. This interface exhibits a signature of strong spin-orbit coupling. Our experimental observations of two fold AMR and PHE at low magnetic fields (B) is similar to those obtained for topological systems and can be intuitively understood using a phenomenological theory for a Rashba spin-split system. Our experimental data show a B2 dependence of AMR and PHE at low magnetic fields that could also be explained based on our model. At high fields (~8 T), we see a two fold to four fold transition in the AMR that could not be explained using only Rashba spin-split energy spectra. Two dimensional electron gas (2DEG) at oxide interfaces is promising in modern electronic devices. Here, Wadehra et al. realize 2DEG at a novel interface composed of LaVO3 and KTaO3, where strong spin-orbit coupling and relativistic nature of the electrons in the 2DEG, leading to anisotropic magnetoresistance and planar Hall effect. [ABSTRACT FROM AUTHOR]

The magnetic, transport, and magnetotransport properties of ferromagnetic Zn0.1Cd0.9GeAs2 + 10% MnAs and Zn0.1Cd0.9GeAs2 + 15% MnAs nanocomposites with a Curie temperature TC ≈ 310–312 K are studied at a high pressure up to 7 GPa and room temperature. The behavior of the magnetic and electronic properties under pressure points to a magnetic transformation and a semiconductor–metal transition, which occur at the same pressure (P ≈ 3.5 GPa). Both compositions exhibit pressure-induced magnetoresistance in the magnetic field range up to H = 5 kOe. As follows from an analysis of the experimental data, the magnetoresistance in the semiconductor–metal transition area is described by a standard p–d model, which takes into account the interaction of carrier spins and the magnetic moment localized at Mn impurities. A giant magnetoresistance is detected in this region: it is maximal in comparison with the magnetoresistance at atmospheric pressure (Δρxx/ρ0 < 1%) for the composition with 15% MnAs clusters. The appearance of enhanced magnetoresistance and the magnetic and electronic phase transformations are mainly caused by pressure-induced changes in the matrix. [ABSTRACT FROM AUTHOR]

The unsaturated magnetization reversal by pulsed current annealing was investigated in exchange biased NiFe(15 nm)/FeMn(10 nm) bilayer. The magnetization reversal was conducted by energizing and thus heating the film under an external applied magnetic field ( H a ) with the direction opposite to the deposition field ( H d ). The static and dynamic magnetic properties of the films before and after rapid annealing were characterized using vibrating sample magnetometer, anisotropic magnetoresistance (AMR) and vector network analyzer measurements. When the samples were annealed at 40 and 45 V condenser voltages, greater values of rotational anisotropy (H rot) , ferromagnetic resonance frequency ( f r ) and smaller values of exchange bias field (H e) , exchange bias field in AMR measurement ( H e MR ), and magnetoresistance in the samples were obtained, which is attributed to the unsaturated reversed magnetization in reversing magnetic field. A suggested model for which the scattered magnetization of magnetic moment results in additional unstable antiferromagnetic spins in the film was proposed to explain this interesting phenomenon. [ABSTRACT FROM AUTHOR]

Nanobiosensors contribute to point-of-care (POC) efforts to make routine biodiagnostics more accessible to patients with respect to both expense and convenience. However, devices whose operation is based on magnetic phenomena appear delayed in their progress toward POC commercialization despite their promise of better sensitivity, as compared to devices based on optical, mechanical, or electrochemical phenomena. This review aims to elucidate the technical challenges preventing magnetic nanobiosensors from reaching market readiness. The following types of magnetic nanobiosensor operation are reviewed: giant magnetic impedance (GMI), superconducting quantum interference device (SQUID), anisotropic magnetoresistance, giant magnetoresistance (GMR), resonant coil, Hall effect, and microcantilever. In particular, a careful comparison of each type in terms of their advantages, disadvantages, recently overcome challenges, and sensitivities will be presented. For example, a disadvantage of GMI sensors, and certain others reviewed here, is the fact that ferromagnetic materials used in their construction directly impact the biosensing event since magnetic nanoparticle (MNP) labels are involved in the strategy. Other challenges associated with use of MNP labels will be addressed. Furthermore, some of the more interesting state-of-the-art magnetic nanobiosensor efforts will be discussed in order to provide an overview of target analytes and sample media under consideration. This review identifies GMR sensors as poised to dominate the market owing to their good sensitivity and ease of use. On the other hand, SQUID sensors, at their current stage of development, are revealed as unsuitable for POC applications due to their high operational cost and unwieldy instrumentation. Magnetics experts endeavoring to progress the field toward commercialization will find this review indispensable. [ABSTRACT FROM AUTHOR]

We report a highly anisotropic magnetoresistance of (Cd0.993Zn0.007)3As2 single crystals, which have been synthesized by the vapor-phase growth. Scanning electron microscopy and electron diffraction data confirm the high crystalline quality of obtained samples. Studied samples exhibit specific features such as octahedral nuclei growth and step-like morphology of the surface formed by {112} planes. The giant anisotropic magnetoresistance and Shubnikov-de Haas oscillations have been observed at low temperatures. The results suggest the existence of the Dirac semimetal phase in (Cd1 −xZnx)3As2 solid solution with low zinc content. Thus, the observed magnetoresistance anisotropy is partially attributed to the chiral anomaly. [ABSTRACT FROM AUTHOR]

Recent studies have shown that the magnetic field sensitivity of an anisotropic magnetoresistance (AMR) sensor using a single-layer Ni80Fe20 thin film can be considerably improved by increasing the shape anisotropy of the film. In this work, an effective approach for improving the sensitivity and reducing the magnetic coercive field as well as the thermal noise contribution in an AMR Wheatstone bridge sensor is proposed by combining multiple resistors in the series-parallel combination circuits. Four different AMR sensor designs, consisting of a single resistor, three and five resistors in series and six resistors in series-parallel connection, were fabricated by using Ta (10 nm)/Ni80Fe20 (5 nm)/Ta (10 nm) films grown on thermally oxidized Si substrates under the presence and the absence of a biasing magnetic field (900 Oe). The results showed that the sensors based on series-parallel combination gain a magnetic sensitivity (SH) 1.72 times higher than that of the sensor based on the series connection. This optimized sensor has improved the capacity of detecting various concentrations of magnetic nanoparticles with a detection limit of magnetic moments estimated to be about 0.56 μemu. [ABSTRACT FROM AUTHOR]

Due to the influence of some factors, the Exchange bias (EB) field (H) that leads us to use different thin film magnetic measurements is different. So we want to give fixed magnetic material parameters in order to explore different methods for the measurement of the EB field. A series of NiFe(15 nm)/FeMn( t ) exchange-biased bilayers were fabricated by magnetron sputtering. Three different methods were used to measure the exchange bias field of the thin films. The first method used a traditional vibrating sample magnetometer (VSM), the second one was the anisotropic magnetoresistance (AMR) technique and the last method was the vector network analyzer ferromagnetic resonance (VNA-FMR) technique. The results show that for the sample at the critical thickness, the exchange bias fields obtained by AMR and VNA-FMR were much larger than those from the VSM, which can be explained by the unstable coupled grains at the interface. For the sample at the saturation thickness, the measurement values of the three methods are almost the same. [ABSTRACT FROM AUTHOR]

The spin-orbit driven phenomena, such as the anisotropic magnetoresistance (AMR), the anomalous Hall conductivity (AHC), and the Gilbert damping in disordered fcc-PdCo alloys were studied from first principles using a unified electronic structure model. In PdCo alloys around equiconcentration composition partial order can exist and we investigate its effect on the transport properties and Gilbert damping. It was found that the partial order significantly improves agreement of the calculated AMR ratio and the experiment as compared to the random alloy case. The influence of ordering on the AHC and the Gilbert damping is much weaker. [ABSTRACT FROM AUTHOR]

The anisotropic magnetic and magnetoelectric properties of single crystals of substituted M-type SrScFeO ( x = 1.4-1.7) hexaferrites are studied at temperatures of 2-800 K in magnetic fields up to 50 kOe. A spontaneous transition from a collinear ferrimagnetic single-axis phase to a conical structure is detected in all compositions, the transition temperature increases with the Sc concentration, and the Curie temperature decreases with increasing Sc concentration. The conical magnetic structures exhibit an electric polarization (more than 40 μC/m at T = 4 K) induced by a magnetic field. The conditions of appearance of the polarization indicate that it is caused by the inverse Dzyaloshinskii-Moriya interaction. The dependences of the polarization on the value and the orientation of a magnetic field are investigated, and the possibilities of controlling the chirality of a conical structure, which determines the sign of polarization, are demonstrated. [ABSTRACT FROM AUTHOR]

In this paper, 1-exact vertex-centered finite-volume schemes with an edge-based approximation of fluxes are constructed for numerically solving hyperbolic problems on hybrid unstructured meshes. The 1-exactness property is ensured by introducing a new type of control volumes, which are called semitransparent cells. The features of a parallel algorithm implementing the computations using semitransparent cells on modern supercomputers are described. The results of solving linear and nonlinear test problems are given. [ABSTRACT FROM AUTHOR]

Conductive bridge random access memory (CBRAM) has been extensively studied as a next-generation non-volatile memory. The conductive filament (CF) shows rich physical effects such as conductance quantization and magnetic effect. But so far, the study of filaments is not very sufficient. In this work, Co/HfO/Pt CBRAM device with magnetic CF was designed and fabricated. By electrical manipulation with a partial-RESET method, we controlled the size of ferromagnetic metal filament. The resistance-temperature characteristics of the ON-state after various partial-RESET behaviors have been studied. Using two kinds of magnetic measurement methods, we measured the anisotropic magnetoresistance (AMR) of the CF at different temperatures to reflect the magnetic structure characteristics. By rotating the direction of the magnetic field and by sweeping the magnitude, we obtained the spatial direction as well as the easy-axis of the CF. The results indicate that the easy-axis of the CF is along the direction perpendicular to the top electrode plane. The maximum magnetoresistance was found to appear when the angle between the direction of magnetic field and that of the electric current in the CF is about 30°, and this angle varies slightly with temperature, indicating that the current is tilted. [ABSTRACT FROM AUTHOR]

The level of residual stresses (RS) in anisotropic electric steel (AES) is its most important functional characteristic that is responsible for losses of electric power in magnetic circuits of transformers during their service life. Reasons are given for the emergence of RS in AES and the known estimation methods are provided, the main shortcoming of the latter being the lack of quantitative estimates of RS. A simple and practically feasible method is suggested for estimating RS based on measurement of the anisotropy of magnetic properties of AES. [ABSTRACT FROM AUTHOR]

The development of high-energy weapons could increase the velocity of projectiles to well over 1000 m/s. The nature of the injuries caused by the ballistic impact of projectiles at velocities much faster than 1000 m/s is unclear. This study characterizes the mechanical and biochemical alterations caused by high-speed ballistic impact generated by spherical steel ball to the hind limbs of the pig. That the local and distal injuries caused by hypervelocity ballistic impact to the living body are also identified. It is showed that the severity of the injury was positively correlated with the velocity of the projectile. And 4000 m/s seems to be the critical velocity for the 5.6 mm spherical steel ball, which would cause severe damage to either local or distal organs, as below that speed the projectile penetrated the body while above that speed it caused severe damage to the body. In addition, vaporization prevented the projectile from penetrating the body and the consequent pressure wave seems to be the causal factor for the distant damage. [ABSTRACT FROM AUTHOR]

We have addressed the magnetic excitations of quasi-one-dimensional two-leg anisotropic antiferromagnetic spin ladder under the influence of longitudinal magnetic field. Such excitations can be obtained via the study of frequency behavior of dynamical spin structure factors. The original spin model hamiltonian can be transformed to a hard core bosonic gas using a generalized bond operator formalism. We have used the linear response theory within Green's function approach to obtain the frequency behavior of both longitudinal and transverse dynamical spin structure factor in the gapful regime. The results show energy gap vanishes at critical magnetic field which depends on anisotropic parameters. We have also found the longitudinal spin structure factor shows a sharp single peak at a particular frequency. The position of this peak moves to lower frequencies with increase of both intersite and local anisotropy parameters. However, the effect of intersite anisotropy on the position of peak in the longitudinal structure factor is more remarkable compared to another one. Also the change of magnetic field shows no considerable effect on the behavior of longitudinal spin structure factor. Furthermore, we have studied the dependence of the transverse structure factor on frequency for different magnetic field and anisotropy parameters. Unlike longitudinal case, two separate peaks appears in the transverse spin structure. The enhancement of magnetic field causes that the peaks in the transverse structure factor become far away from each other. Also, the influences of both anisotropies on the spin excitation spectrum of transverse spin components have been discussed. [ABSTRACT FROM AUTHOR]

This paper describes the tensile properties, flow and work-hardening behavior of four metastable β-titanium alloys Ti-5Al-5Mo-5V-3Cr (A1), Ti-5Al-3.5Mo-7.2V-3Cr (A2), Ti-5Al-5Mo-8.6V-1.5Cr (A3), and Ti-5Al-3.5Mo-5V-3.94Cr (A4) in α+β hot-rolled condition. The decreasing order of average strength parameters ( σ and σ) is A4, A2, A1, and A3. The maximum strength observed in alloy A4 is due to the presence of highest wt. fraction of Cr. The elongation is the maximum and minimum in alloys A3 and A4, respectively. These alloys display moderate to high percent in-plane anisotropy ( A) and reasonably low anisotropic index ( δ) values. Both the A and δ values are maximum and minimum in alloys A1 and A3, respectively. The yield locus plots also exhibit the presence of anisotropy due to relatively large differences in yield strength values along tension and compression directions. The flow behavior of alloys A1, A2, and A4 follows Swift equation, while the alloy A3 displays best fit with Holloman equation. The presence of prestrain ( ε) in hot-rolled materials before tensile testing has an important bearing on the flow curves of A1, A2, and A4 alloys. The instantaneous work-hardening rate curves of the alloys A1, A2, and A3 exhibit all the three typical stages (stage I, stage II, and stage III) in RD samples, while the alloy A4 shows the presence of only stage I and stage III. The 45 deg to RD and TD samples of alloys A1, A2, and A4 display only stage I. The stages I and III as well as I and II are present in alloy A3 in 45 deg to RD and TD samples, respectively. Dislocation-controlled strain hardening occurs in all the three stages of these alloys in the absence of stress-induced martensitic transformation (α″) and twinning. Slip is the predominant deformation mechanism during tensile testing. Three types of slip lines, i.e., planar, wavy, and intersecting have been observed close to fracture surfaces of post tensile-tested specimens. [ABSTRACT FROM AUTHOR]

The anisotropic characteristics of an iron silicide (FeSi) epitaxial thin magnetic film grown on a Si(111) silicon vicinal surface with a misorientation angle of 0.14° have been measured by the ferromagnetic resonance method. It has been shown that the polar and azimuth misorientation angles of the crystallographic plane of the substrate can be determined simultaneously from the angular dependences of the ferromagnetic resonance field of the epitaxial film. The effective saturation magnetization of the film M = 1105 G and the constant of the cubic magnetocrystalline anisotropy K = 1.15 × 10 erg/cm have been determined. The misorientation of the substrate plane leads to the formation of steps on the film surface and, as a result, to the appearance of uniaxial magnetic anisotropy of the magnetic dipole nature with the constant K = 796 erg/cm. Small unidirectional magnetic anisotropy ( K = 163 erg/cm), which may be associated with symmetry breaking on the steps of the film and is due to the Dzyaloshinskii-Moriya interaction, has been detected. [ABSTRACT FROM AUTHOR]

The results of studies on the fabrication and optimization of the configuration of magnetic-field sensors based on anisotropic magnetoresistive thin-film structures are described. Magnetic-field sensors with an odd characteristic and a sensitivity to 23.7 (mV/V)/(kA/m) and a 180° angle-rotation sensor with a signal amplitude of 15 mV/V are obtained. Based on the performed thermal tests, the possibility of applying the developed sensors in extreme environments in the temperature range from -60 to +150°C is shown, and the temperature-sensitivity coefficient amounts to -0.35%/°C. The obtained sensors are tested in angle, speed, and phase sensors in the automobile industry. The characteristics of the developed sensors correspond to the analogues of leading world firms. [ABSTRACT FROM AUTHOR]

The dispersion equation of a strongly anisotropic one-dimensional magnet catena-[Fe(ClO){Fe(bpca)}]ClO containing alternating high-spin (HS) ( S = 2) and low-spin (LS) ( S = 1/2) iron ions is obtained by the diagram technique for Hubbard operators. The analysis of this equation yields six branches in the excitation spectrum of this magnet. It is important that the crystal field for ions with spin S = 2 is described by the Hamiltonian of single-ion easy-plane anisotropy, whose orientation is changed by 90° when passing from one HS iron ion to another. The U( N) transformation technique in the atomic representation is applied to diagonalize a single-ion Hamiltonian with a large number of levels. It is shown that the modulation of the orientation of easy magnetization planes leads to a model of a ferrimagnet with easy-axis anisotropy and to the formation of energy spectrum with a large gap. For HS iron ions, a decrease in the mean value of the spin projection due to quantum fluctuations is calculated. The analysis of the specific features of the spectrum of elementary excitations allows one to establish a correspondence to a generalized Ising model for which the magnetic susceptibility is calculated in a wide range of temperatures by the transfer-matrix method. The introduction of a statistical ensemble that takes into account the presence of chains of different lengths and the presence of iron ions with different spins allows one to describe the experimentally observed modification of the magnetic susceptibility of the magnet under optical irradiation. [ABSTRACT FROM AUTHOR]

Elastoacoustic coupling coefficients (EACCs) are links between acoustic parameters and mechanical stresses during their determination by the acoustoelasticity method. The magnitudes of the EACCs of a structural material can be calculated if its elasticity constants of the second and third orders are known or determined experimentally for a known stress state of a material. Unfortunately, the calculation variant is little used practically because not all moduli of nonlinear elasticity of even basic structural materials are known with sufficient accuracy. Here, the results are given of the experimental determination of the magnitudes of EACCs for three grades of low-alloy structural steels with different magnitudes of proper acoustic anisotropy, which is determined by the anisotropy of the elastic properties of a material. During the mechanical tests, samples were subjected to uniaxial tension at stepped load magnitudes. They were cut from longitudinal welded tubes of the K60 strength class, which are applied in the mounting of a linear section of gas-main pipelines. Experiments were carried out using an acoustic bench (based on an I2-26 off-the-shelf device) and an IN-5101A automated device that was developed by the ENCOTES Engineering firm, which use the ultrasonic echo method for nondestructive testing. The results of the acoustomechanical tests showed that during the calculation of biaxial stresses according to the data of precise ultrasonic measurements in pipe steels with a magnitude of greater than 3% for the proper acoustic anisotropy, computational algorithms that take the differences of the magnitudes of EACCs into account for stresses that work along and across the direction of the rolling of pipe steel should be used, i.e., along and across the longitudinal axis of the pipe. [ABSTRACT FROM AUTHOR]