Showing papers on "Colossal magnetoresistance published in 2017"
TL;DR: In chains of InSb-Ag nanoparticles at room temperature, it is found that the resistance can be increased by almost a factor of 2 with magnetic fields of 2 T, and it is shown that this important change results from the strong spectral dependence of localized surface waves on the magnitude of the magnetic field.
Abstract: A giant thermal magnetoresistance is predicted for the electromagnetic transport of heat in magneto-optical plasmonic structures. In chains of InSb-Ag nanoparticles at room temperature, we find that the resistance can be increased by almost a factor of 2 with magnetic fields of 2 T. We show that this important change results from the strong spectral dependence of localized surface waves on the magnitude of the magnetic field.
85 citations
TL;DR: In this article, an alternative approach to obtaining tunneling anisotropic magnetoresistance in α-FeRh-based junctions driven by the magnetic phase transition of α−FeRh and resultantly large variation of the density of states in the vicinity of the MgO tunneling barrier is presented.
Abstract: The independent control of two magnetic electrodes and spin-coherent transport in magnetic tunnel junctions are strictly required for tunneling magnetoresistance, while junctions with only one ferromagnetic electrode exhibit tunneling anisotropic magnetoresistance dependent on the anisotropic density of states with no room temperature performance so far. Here, we report an alternative approach to obtaining tunneling anisotropic magnetoresistance in α′-FeRh-based junctions driven by the magnetic phase transition of α′-FeRh and resultantly large variation of the density of states in the vicinity of MgO tunneling barrier, referred to as phase transition tunneling anisotropic magnetoresistance. The junctions with only one α′-FeRh magnetic electrode show a magnetoresistance ratio up to 20% at room temperature. Both the polarity and magnitude of the phase transition tunneling anisotropic magnetoresistance can be modulated by interfacial engineering at the α′-FeRh/MgO interface. Besides the fundamental significance, our finding might add a different dimension to magnetic random access memory and antiferromagnet spintronics. Tunneling anisotropic magnetoresistance is promising for next generation memory devices but limited by the low efficiency and functioning temperature. Here the authors achieved 20% tunneling anisotropic magnetoresistance at room temperature in magnetic tunnel junctions with one α′-FeRh magnetic electrode.
53 citations
TL;DR: Strong diamagnetism in the Mott insulator calcium ruthenate (Ca2RuO4) induced by dc electric current is reported, suggesting that dc current may be a means to control the properties of materials in the vicinity of a Mottinsulator transition.
Abstract: Mott insulators can host a surprisingly diverse set of quantum phenomena when their frozen electrons are perturbed by various stimuli. Superconductivity, metal-insulator transition, and colossal magnetoresistance induced by element substitution, pressure, and magnetic field are prominent examples. Here we report strong diamagnetism in the Mott insulator calcium ruthenate (Ca2RuO4) induced by dc electric current. The application of a current density of merely 1 ampere per centimeter squared induces diamagnetism stronger than that in other nonsuperconducting materials. This change is coincident with changes in the transport properties as the system becomes semimetallic. These findings suggest that dc current may be a means to control the properties of materials in the vicinity of a Mott insulating transition.
48 citations
TL;DR: In this paper, the role of the lattice in charge-ordered states remains particularly enigmatic, soliciting characterization of the microscopic lattice behavior, and the authors directly map picometer scale periodic lattice displacements at individual atomic columns in the room temperature chargeordered manganite Bi0.35Sr0.18Ca0.47MnO3 using aberration-corrected scanning transmission electron microscopy.
Abstract: In charge-ordered phases, broken translational symmetry emerges from couplings between charge, spin, lattice, or orbital degrees of freedom, giving rise to remarkable phenomena such as colossal magnetoresistance and metal-insulator transitions. The role of the lattice in charge-ordered states remains particularly enigmatic, soliciting characterization of the microscopic lattice behavior. Here we directly map picometer scale periodic lattice displacements at individual atomic columns in the room temperature charge-ordered manganite Bi0.35Sr0.18Ca0.47MnO3 using aberration-corrected scanning transmission electron microscopy. We measure transverse, displacive lattice modulations of the cations, distinct from existing manganite charge-order models. We reveal locally unidirectional striped domains as small as ~5 nm, despite apparent bidirectionality over larger length scales. Further, we observe a direct link between disorder in one lattice modulation, in the form of dislocations and shear deformations, and nascent order in the perpendicular modulation. By examining the defects and symmetries of periodic lattice displacements near the charge ordering phase transition, we directly visualize the local competition underpinning spatial heterogeneity in a complex oxide.
47 citations
TL;DR: Mechanisms and physical consequence of charge transfer across interfaces in oxide heterostructures are reviewed and theoretical methods that are used to calculate chargeTransfer across oxide interfaces are reviewed.
Abstract: Complex oxides exhibit many intriguing phenomena, including metal-insulator transition, ferroelectricity/multiferroicity, colossal magnetoresistance and high transition temperature superconductivity. Advances in epitaxial thin film growth techniques enable us to combine different complex oxides with atomic precision and form an oxide heterostructure. Recent theoretical and experimental work has shown that charge transfer across oxide interfaces generally occurs and leads to a great diversity of emergent interfacial properties which are not exhibited by bulk constituents. In this report, we review mechanisms and physical consequence of charge transfer across interfaces in oxide heterostructures. Both theoretical proposals and experimental measurements of various oxide heterostructures are discussed and compared. We also review the theoretical methods that are used to calculate charge transfer across oxide interfaces and discuss the success and challenges in theory. Finally, we present a summary and perspectives for future research.
46 citations
TL;DR: In this paper, angle resolved Raman spectroscopy was used to study the Raman dependence of 1'T'-MoTe2 on different layer numbers and excitation energies.
Abstract: The recently discovered two-dimensional (2D) semimetal 1 T´-MoTe2 exhibits colossal magnetoresistance and superconductivity, driving a strong research interest in the material’s quantum phenomena. Unlike the typical hexagonal structure found in many 2D materials, the 1 T´-MoTe2 lattice has strong in-plane anisotropy. A full understanding of the anisotropy is necessary for the fabrication of future devices which may exploit these quantum and topological properties, yet a detailed study of the material’s anisotropy is currently lacking. While angle resolved Raman spectroscopy has been used to study anisotropic 2D materials, such as black phosphorus, there has been no in-depth study of the Raman dependence of 1 T´-MoTe2 on different layer numbers and excitation energies. Here, our angle resolved Raman spectroscopy shows intricate Raman anisotropy dependences of 1 T´-MoTe2 on polarization, flake thickness (from single layer to bulk), photon, and phonon energies. Using a Paczek approximation, the anisotropic Raman response can be captured in a classical framework. Quantum mechanically, first-principle calculations and group theory reveal that the anisotropic electron-photon and electron-phonon interactions are nontrivial in the observed responses. This study is a crucial step to enable potential applications of 1 T´-MoTe2 in novel electronic and optoelectronic devices where the anisotropic properties might be utilized for increased functionality and performance.
45 citations
TL;DR: The perovskite La2CrMnO6 has a Griffith-like phase with the occurrence of ferromagnetic short range correlations above TC and the system ultimately turns into paramagnetic at the Griffiths temperature 180 K as discussed by the authors.
Abstract: DC and AC magnetic measurements indicate the presence of multiple magnetic transitions arising from the competing magnetic interaction between Cr and Mn in the perovskite La2CrMnO6. Ferromagnetic and spin glass transitions are observed in La2CrMnO6. The material also has a Griffith-like phase with the occurrence of ferromagnetic short range correlations above TC. The system ultimately turns into paramagnetic at the Griffiths temperature 180 K. A combination of variable range hopping, and the nearest neighbor small polaron hopping governs the conduction mechanism in the material. A negative magnetoresistance of 22% at 105 K is observed for the material at 90 kOe which increases to 29% near 110 K and reduces gradually to zero on further increase in the temperature.
44 citations
TL;DR: It is shown that the quasilinear magnetoresistance may arise from an intricate interplay between a nontrivial band crossing protected by nonsymmorphic crystal symmetry and strong magnetic fluctuations.
Abstract: In conventional metals, modification of electron trajectories under magnetic field gives rise to a magnetoresistance that varies quadratically at low field, followed by a saturation at high field for closed orbits on the Fermi surface. Deviations from the conventional behaviour, for example, the observation of a linear magnetoresistance, or a non-saturating magnetoresistance, have been attributed to exotic electron scattering mechanisms. Recently, linear magnetoresistance has been observed in many Dirac materials, in which the electron–electron correlation is relatively weak. The strongly correlated helimagnet CrAs undergoes a quantum phase transition to a nonmagnetic superconductor under pressure. Here we observe, near the magnetic instability, a large and non-saturating quasilinear magnetoresistance from the upper critical field to 14 T at low temperatures. We show that the quasilinear magnetoresistance may arise from an intricate interplay between a nontrivial band crossing protected by nonsymmorphic crystal symmetry and strong magnetic fluctuations. The electronic structure of the helimagnet CrAs is unusual due to its nonsymmorphic crystal symmetry. Here, the authors observe quasilinear magnetoresistance close to a pressure-driven superconducting transition, which may arise from the interaction of the band structure and magnetic fluctuations.
40 citations
TL;DR: Observations made in this work are remarkably similar to those made in complex oxide materials, including high-temperature superconductors, but highly extraordinary within the realm of conventional sp-bonded semiconductor materials, suggesting that exotic quantum matter phases can be realized and engineered on silicon-based materials platforms.
Abstract: The physics of doped Mott insulators is at the heart of some of the most exotic physical phenomena in materials research including insulator-metal transitions, colossal magnetoresistance, and high-temperature superconductivity in layered perovskite compounds. Advances in this field would greatly benefit from the availability of new material systems with a similar richness of physical phenomena but with fewer chemical and structural complications in comparison to oxides. Using scanning tunneling microscopy and spectroscopy, we show that such a system can be realized on a silicon platform. The adsorption of one-third monolayer of Sn atoms on a Si(111) surface produces a triangular surface lattice with half filled dangling bond orbitals. Modulation hole doping of these dangling bonds unveils clear hallmarks of Mott physics, such as spectral weight transfer and the formation of quasiparticle states at the Fermi level, well-defined Fermi contour segments, and a sharp singularity in the density of states. These observations are remarkably similar to those made in complex oxide materials, including high-temperature superconductors, but highly extraordinary within the realm of conventional sp-bonded semiconductor materials. It suggests that exotic quantum matter phases can be realized and engineered on silicon-based materials platforms.
34 citations
30 citations
TL;DR: The results suggest that graphene and hexagonal boron nitride nanoribbon heterostructures may have potential applications in graphene-based nanodevices.
Abstract: Thermal spin transport properties of graphene and hexagonal boron nitride nanoribbon heterojunctions have been investigated using density functional theory calculations combined with the Keldysh nonequilibrium Green's function approach. The results showed that the perfect spin Seebeck effect and analogy negative differential thermoelectric resistance occurred in the device under a temperature difference without a gate or bias voltage. An intriguing thermally induced colossal magnetoresistance without gate regulation was also observed, which can be switched between a positive and negative value with temperature control. It was also found that the unit number of zigzag graphene nanoribbons and boron nitride nanoribbons can tune the electronic band structure and the energy gap of the heterostructure, and then modulate the thermal spin transport properties. The results suggest that graphene and hexagonal boron nitride nanoribbon heterostructures may have potential applications in graphene-based nanodevices.
TL;DR: A spin filtering model based on Zeeman effect and direct tunneling is developed to account for MR of the phase separated films, leading to a sizable MR effect in epitaxial spinel films.
Abstract: The coexistence of ferromagnetic metallic phase and antiferromagnetic insulating phase in nanoscaled inhomogeneous perovskite oxides accounts for the colossal magnetoresistance. Although the model of spin-polarized electron transport across antiphase boundaries has been commonly employed to account for large magnetoresistance (MR) in ferrites, the magnetic anomalies, the two magnetic phases and enhanced molecular moment, are still unresolved. We observed a sizable MR in epitaxial spinel films (NiCo2O4−δ) that is much larger than that commonly observed in spinel ferrites. Detailed analysis reveals that this MR can be attributed to phase separation, in which the perfect ferrimagnetic metallic phase and ferrimagnetic insulating phase coexist. The magnetic insulating phase plays an important role in spin filtering in these phase separated spinel oxides, leading to a sizable MR effect. A spin filtering model based on Zeeman effect and direct tunneling is developed to account for MR of the phase separated films.
TL;DR: In this paper, the authors study the CMR parent compound LaMnO using total scattering to understand its orbital order/disorder transition and find a discontinuous change in local structure that indicates a fundamental change in the type of orbital arrangement at the transition.
Abstract: Orbital degrees of freedom are a key ingredient in unconventional physics, including colossal magnetoresistance (CMR). When ordered, orbital arrangements can be characterized using conventional crystallographic approaches. Yet CMR emerges from states of orbital disorder, for which the experimental signature is much more ambiguous. Here, the authors study the CMR parent compound LaMnO${}_{3}$, using total scattering to understand its orbital order/disorder transition. They find a discontinuous change in local structure that indicates a fundamental change in the type of orbital arrangement at the transition. The analysis highlights the difficulty of discriminating between local structural models when static and dynamic disorder are strongly coupled.
TL;DR: In this article, double perovskite La 2 Co 1−x Fe x MnO 6 samples were synthesized by the standard solid-state reaction method, and the powder x-ray diffraction (Cu- Kα ) results confirm that this type of compounds has orthorhombic pervskite structure with space group of Pbnm at room temperature.
TL;DR: In this article, a giant crystalline AMR as large as 57% to 104% in anisotropic quantum wells based on nonmagnetic perovskite oxides was shown.
Abstract: Anisotropic magnetoresistance (AMR) was observed by Lord Kelvin one-and-half centuries ago in iron and nickel. The resistance of these ferromagnetic conductors showed a few percent change when a magnetic field was applied along or across the current. Subsequently, a 20% AMR was demonstrated in alloys of nickel and iron (permalloys). Efforts have then been devoted to extend this effect in multifunctional materials. The oxide heterostructure exhibiting two-dimensional electron liquid is one of the potential candidates as it has shown to exhibit emergent magnetic ordering, strong spin-orbit interactions, and anisotropic magnetoresistance. Here we show a giant crystalline AMR as large as 57% to 104% in anisotropic quantum wells based on nonmagnetic perovskite oxides $\mathrm{LaAl}{\mathrm{O}}_{3}$ and $\mathrm{SrTi}{\mathrm{O}}_{3}$, providing an alternative way in tailoring AMR with an extremely large effect. The AMR maximum appears when the magnetic field points along the in-plane $[1\overline{1}0]$ direction, irrespective of the direction of current flow, which is consistent with the idea of crystalline AMR. Data analysis and density functional theory calculation show that the observed giant crystalline AMR mainly originates from the strong anisotropic spin-orbit field at the interface due to its unique elliptical Fermi surface related to its orbital configuration and reconstruction. This work demonstrates that perovskite oxide interface is a unique platform for orbital physics.
TL;DR: Results suggest that colossal magnetoresistance at THz frequencies may find use in nanoelectronics and in THz optical components controlled by magnetic fields, and the VAN can be scaled in thickness while retaining a high structural quality and offers a larger THz CMR at room temperature than the planar film.
Abstract: Colossal magnetoresistance (CMR) is demonstrated at terahertz (THz) frequencies by using terahertz time-domain magnetospectroscopy to examine vertically aligned nanocomposites (VANs) and planar thin films of La0.7Sr0.3MnO3. At the Curie temperature (room temperature), the THz conductivity of the VAN was dramatically enhanced by over 2 orders of magnitude under the application of a magnetic field with a non-Drude THz conductivity that increased with frequency. The direct current (dc) CMR of the VAN is controlled by extrinsic magnetotransport mechanisms such as spin-polarized tunneling between nanograins. In contrast, we find that THz CMR is dominated by intrinsic, intragrain transport: the mean free path was smaller than the nanocolumn size, and the planar thin-film exhibited similar THz CMR to the VAN. Surprisingly, the observed colossal THz magnetoresistance suggests that the magnetoresistance can be large for alternating current motion on nanometer length scales, even when the magnetoresistance is negli...
TL;DR: The results suggest the interpretation that the Idc serves to suppress scattering between states near the Fermi level in a strong magnetic field limit.
Abstract: Radiation-induced magnetoresistance oscillations are examined in the GaAs/AlGaAs 2D system in the regime where an observed concurrent giant magnetoresistance is systematically varied with a supplementary dc-current, I
dc
. The I
dc
tuned giant magnetoresistance is subsequently separated from the photo-excited oscillatory resistance using a multi-conduction model in order to examine the interplay between the two effects. The results show that the invoked multiconduction model describes the observed giant magnetoresistance effect even in the presence of radiation-induced magnetoresistance oscillations, the magnetoresistance oscillations do not modify the giant magnetoresistance, and the magnetoresistance oscillatory extrema, i.e., maxima and minima, disappear rather asymmetrically with increasing I
dc
. The results suggest the interpretation that the I
dc
serves to suppress scattering between states near the Fermi level in a strong magnetic field limit.
TL;DR: In this article, an extrinsic magnetic anisotropy was used to induce a dominant switchable magnetoresistance in La 0.7Sr0.3MnO3 epitaxial films at room temperature (RT).
Abstract: The magnetoresistance (MR) effect is widely used in technologies that pervade the world, from magnetic reading heads to sensors. Diverse contributions to MR, such as anisotropic, giant, tunnel, colossal, and spin-Hall, are revealed in materials depending on the specific system and measuring configuration. Half-metallic manganites hold promise for spintronic applications but the complexity of competing interactions has not permitted the understanding and control of their magnetotransport properties to enable the realization of their technological potential. This study reports on the ability to induce a dominant switchable magnetoresistance in La0.7Sr0.3MnO3 epitaxial films at room temperature (RT). By engineering an extrinsic magnetic anisotropy, a large enhancement of anisotropic magnetoresistance (AMR) is achieved which at RT leads to signal changes much larger than the other contributions such as the colossal magnetoresistance. The dominant extrinsic AMR exhibits large variation in the resistance in low field region, showing high sensitivity to applied low magnetic fields. These findings have a strong impact on the real applications of manganite-based devices for the high-resolution low field magnetic sensors or spintronics.
TL;DR: By using the non-equilibrium Green’s function with density functional theory, the thermal spin transport properties of Fe-C6 cluster doped monolayer MoS2 are studied and it is shown that the device has a perfect Seebeck effect under temperature difference without gate voltage or bias voltage.
Abstract: By using the non-equilibrium Green's function with density functional theory, we have studied the thermal spin transport properties of Fe-C6 cluster doped monolayer MoS2. The results show that the device has a perfect Seebeck effect under temperature difference without gate voltage or bias voltage. Moreover, we also find the thermal colossal magnetoresistance effect, which is as high as 107%. The competition between spin up electrons and spin down holes of the parallel spin configuration leads to peculiar behavior of colossal magnetoresistance and thermo-current, which is essential for the design of thermal transistors. These results are useful in future MoS2-based multifunctional spin caloritronic devices.
TL;DR: In this article, the authors investigated the persistent magnetoresistance effects in phase-separated Pr0.3PbTiO3 heterostructures under a low magnetic field.
Abstract: Persistent magnetoresistance effects in the phase-separated Pr0.65(Ca0.25Sr0.75)0.35MnO3/SrTiO3 and Pr0.65(Ca0.25Sr0.75)0.35MnO3/0.7PbMg1/3Nb2/3O3–0.3PbTiO3 heterostructures under a low magnetic field are investigated. It is observed that the persistent magnetoresistance effects decrease with increasing temperatures and the values for the heterostructures on 0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 and SrTiO3 substrates are about 86.6% and 33.2% at 40 K, respectively. More interestingly, the applied electric field on the 0.7PbMg1/3Nb2/3O3–0.3PbTiO3 substrate can suppress the persistent magnetoresistance effect, indicating that different energy landscapes can be dramatically modulated by the piezo-strain. These results are discussed in terms of the strain-induced competition in the ferromagnetic state and the charge-ordering phase by the energy scenario, which provide a promising approach for designing devices of electric-magnetic memories in all-oxide heterostructures.
TL;DR: In this article, the structural, electrical, and magnetic properties of La0.67Sr0.33Mn1−xCrxO3 (0 ≤ x ≤ 0.10) manganites have been studied by substitution of antiferromagnetic trivalent Cr ion at Mn-site.
TL;DR: In this paper, a large linear-in-field magnetoresistance was demonstrated for a transiton-metal stannide with topological node arcs in the tetragonal phase.
Abstract: Materials exhibiting large magnetoresistance may not only be of fundamental research interest, but also can lead to wide-ranging applications in magnetic sensors and switches. Here we demonstrate a large linear-in-field magnetoresistance, $\Delta \rho/\rho$ reaching as high as $\sim$600$\%$ at 2 K under a 9 Tesla field, in the tetragonal phase of a transiton-metal stannide $\beta$-RhSn$_4$. Detailed analyses show that its magnetic responses are overall inconsistent with the classical model based on the multiple electron scattering by mobility fluctuations in an inhomogenous conductor, but rather in line with the quantum effects due to the presence of Dirac-like dispersions in the electronic structure. Our results may help guiding the future quest for quantum magnetoresistive materials into the family of stannides, similar to the role played by PtSn$_4$ with topological node arcs.
TL;DR: In this paper, the effects of the annealing process on the physical properties of the SPS sample were detailedly discussed and studied, and the TEM results confirmed that the process can effectively suppress the impurity phase SrMoO 4, simultaneously increase the size of the SFMO crystal grains and improve the homogeneity of the crystal grains.
TL;DR: In this article, the authors report an unusual slowing down of the recovery of an electronic phase across a first-order phase transition, far beyond thermal relaxation time, and show that the pseudo-critical dynamics that originates from magnetic interactions close to a weakly first-organised phase transition corresponds to the magnetic interactions.
Abstract: Ordered electronic phases are intimately related to emerging phenomena such as high Tc superconductivity and colossal magnetoresistance. The coupling of electronic charge with other degrees of freedom such as lattice and spin are of central interest in correlated systems. Their correlations have been intensively studied from femtosecond to picosecond time scales, while the dynamics of ordered electronic phases beyond nanoseconds are usually assumed to follow a trivia thermally driven recovery. Here, we report an unusual slowing down of the recovery of an electronic phase across a first-order phase transition, far beyond thermal relaxation time. Following optical excitation, the recovery time of both transient optical reflectivity and x-ray diffraction intensity from a charge-ordered superstructure in a La$_{1/3}$Sr$_{2/3}$FeO$_3$ thin film increases by orders of magnitude longer than the independently measured lattice cooling time when the sample temperature approaches the phase transition temperature. The combined experimental and theoretical investigations show that the slowing down of electronic recovery corresponds to the pseudo-critical dynamics that originates from magnetic interactions close to a weakly first-order phase transition. This extraordinary long electronic recovery time exemplifies an interplay of ordered electronic phases with magnetism beyond thermal processes in correlated systems.
TL;DR: The results indicate that thermally-induced spin polarized currents can be tuned by switching the magnetic configurations, resulting in a perfect thermal colossal magnetoresistance effect.
Abstract: Graphene nanoribbon is a popular material in spintronics owing to its unique electronic properties. Here, we propose a novel spin caloritronics device based on zigzag graphene nanoribbon (ZGNR), which is a heterojunction consisting of a pure single-hydrogen-terminated ZGNR and one doped with nitrogen and boron. Using the density functional theory combined with the non-equilibrium Green’s function, we investigate the thermal spin transport properties of the heterojunction under different magnetic configurations only by a temperature gradient without an external gate or bias voltage. Our results indicate that thermally-induced spin polarized currents can be tuned by switching the magnetic configurations, resulting in a perfect thermal colossal magnetoresistance effect. The heterojunctions with different magnetic configurations exhibit a variety of excellent transport characteristics, including the spin-Seebeck effect, the spin-filtering effect, the temperature switching effect, the negative differential thermal resistance effect and the spin-Seebeck diode feature, which makes the heterojunction a promising candidate for high-efficiently multifunctional spin caloritronic applications.
TL;DR: Based on the structural and magnetoresistive properties of Gd1−xCaxMnO3 (GCMO) (0 ≤ x ≤ 1 ) polycrystalline manganites, the magnetic phase diagram of GCMO is deduced as mentioned in this paper.
TL;DR: In this article, temperature and magnetic field dependence of transport properties in epitaxial films of the manganite La 1− x Ca x MnO 3 in the overdoped region of the phase diagram for x > 0.5, where a charge-ordered (CO) and an antiferromagnetic (AF) phase are present.
TL;DR: In this article, the authors proposed a gate-induced full-polarization reversal in the free ferromagnet, which results in a metal-state to insulator state transition in the device.
Abstract: A colossal magnetoresistance ($\sim 100\times10^3\%$) and an extremely large magnetoresistance ($\sim 1\times10^6\%$) have been previously explored in manganite perovskites and Dirac materials, respectively. However, the requirement of an extremely strong magnetic field (and an extremely low temperature) makes them not applicable for realistic devices. In this work, we propose a device that can generate even larger changes in resistance in a zero-magnetic field and at a high temperature. The device is composed of a graphene under two strips of yttrium iron garnet (YIG), where two gate voltages are applied to cancel the heavy charge doping in the YIG-induced half-metallic ferromagnets. By calculations using the Landauer-Buttiker formalism, we demonstrate that, when a proper gate voltage is applied on the free ferromagnet, changes in resistance up to $305\times10^6\%$ ($16\times10^3\%$) can be achieved at the liquid helium (nitrogen) temperature and in a zero magnetic field. We attribute such a remarkable effect to a gate-induced full-polarization reversal in the free ferromagnet, which results in a metal-state to insulator-state transition in the device. We also find that, the proposed effect can be realized in devices using other magnetic insulators such as EuO and EuS. Our work should be helpful for developing a realistic switching device that is energy saving and CMOS-technology compatible.
TL;DR: In this paper, the spin polarization due to spin-Hall effect is the underlying cause of the enhanced negative magnetoresistance observed in the bilayer of Ni 80 Fe 20 (50nm)/p-Si bilayer.
TL;DR: In this article, the magnetotransport properties of a topological insulator material Ru2Sn3 were studied by growing single crystals of the material using a Bi-Flux method.
Abstract: We have studied magnetotransport properties of a topological insulator material Ru2Sn3. Bulk single crystals of Ru2Sn3 were grown by a Bi flux method. The resistivity is semiconducting at high temperatures above 160 K, while it becomes metallic below 160 K. Nonlinear field dependence of Hall resistivity in the metallic region shows conduction of multiple carriers at low temperatures. In the high-temperature semiconducting region, magnetoresistance exhibits a conventional quadratic magnetic-field dependence. In the low-temperature metallic region, however, high-field magnetoresistance is clearly linear with magnetic fields, signaling a linear dispersion in the low-temperature electronic structure. Small changes in the magnetoresistance magnitude with respect to the magnetic field angle indicate that bulk electron carriers are responsible mainly for the observed linear magnetoresistance.