Showing papers on "Colossal magnetoresistance published in 2016"
TL;DR: It is shown that this Hanle magnetoresistance is an alternative simple way to quantitatively study the coupling between charge and spin currents in metals with strong spin-orbit coupling.
Abstract: We report measurements of a new type of magnetoresistance in Pt and Ta thin films. The spin accumulation created at the surfaces of the film by the spin Hall effect decreases in a magnetic field because of the Hanle effect, resulting in an increase of the electrical resistance as predicted by Dyakonov [Phys. Rev. Lett. 99, 126601 (2007)]. The angular dependence of this magnetoresistance resembles the recently discovered spin Hall magnetoresistance in Pt/Y(3)Fe(5)O(12) bilayers, although the presence of a ferromagnetic insulator is not required. We show that this Hanle magnetoresistance is an alternative simple way to quantitatively study the coupling between charge and spin currents in metals with strong spin-orbit coupling.
146 citations
TL;DR: It is found that, even when the magnetization is saturated, the resistance increases with increasing the magnetic-field strength, which is attributed to the Hanle magnetoresistance in this system.
Abstract: We report the observation of magnetoresistance originating from Rashba spin-orbit coupling (SOC) in a metallic heterostructure: the Rashba-Edelstein (RE) magnetoresistance. We show that the simultaneous action of the direct and inverse RE effects in a $\mathrm{Bi}/\mathrm{Ag}/\mathrm{CoFeB}$ trilayer couples current-induced spin accumulation to the electric resistance. The electric resistance changes with the magnetic-field angle, reminiscent of the spin Hall magnetoresistance, despite the fact that bulk SOC is not responsible for the magnetoresistance. We further found that, even when the magnetization is saturated, the resistance increases with increasing the magnetic-field strength, which is attributed to the Hanle magnetoresistance in this system.
116 citations
TL;DR: FeRh is illustrated as a mixed-phase model system well similar to phase-separated colossal magnetoresistance systems with phase instability therein, which is in contrast to the large volume expansion in the conventional temperature-driven magnetic phase transition in FeRh.
Abstract: We report a giant, ∼22%, electroresistance modulation for a metallic alloy above room temperature. It is achieved by a small electric field of 2 kV/cm via piezoelectric strain-mediated magnetoelectric coupling and the resulting magnetic phase transition in epitaxial FeRh/BaTiO_{3} heterostructures. This work presents detailed experimental evidence for an isothermal magnetic phase transition driven by tetragonality modulation in FeRh thin films, which is in contrast to the large volume expansion in the conventional temperature-driven magnetic phase transition in FeRh. Moreover, all the experimental results in this work illustrate FeRh as a mixed-phase model system well similar to phase-separated colossal magnetoresistance systems with phase instability therein.
102 citations
TL;DR: In this article, the spin-polarization dependence of the electron mobility in the FM layer acting in concert with the spin accumulation induced in that layer by the spin Hall current originating in the bulk of the HM layer is attributed.
Abstract: Recent experiments have revealed nonlinear features of the magnetoresistance in metallic bilayers consisting of a heavy metal (HM) and a ferromagnetic metal (FM). A small change in the longitudinal resistance of the bilayer has been observed when reversing the direction of either the applied in-plane current or the magnetization. We attribute such nonlinear transport behavior to the spin-polarization dependence of the electron mobility in the FM layer acting in concert with the spin accumulation induced in that layer by the spin Hall current originating in the bulk of the HM layer. An explicit expression for the nonlinear magnetoresistance is derived based on a simple drift-diffusion model, which shows that the nonlinear magnetoresistance appears at the first order of the spin Hall angle, and changes sign when the current is reversed, in agreement with the experimental observations. We also discuss possible ways to control sign of the nonlinear magnetoresistance and to enhance the magnitude of the effect.
77 citations
TL;DR: In this article, the authors reported the observation of extremely large magnetoresistance as 3.0$\times$10$^4$ % measured at 2 K and 9 T magnetic field aligned along [001]-ZrSiS.
Abstract: Recently, the extremely large magnetoresistance observed in transition metal telluride, like WTe$_2$, attracted much attention because of the potential applications in magnetic sensor. Here we report the observation of extremely large magnetoresistance as 3.0$\times$10$^4$ % measured at 2 K and 9 T magnetic field aligned along [001]-ZrSiS. The significant magnetoresistance change (~1.4$\times$10$^4$ %) can be obtained when the magnetic field is titled from [001] to [011]-ZrSiS. These abnormal magnetoresistance behaviors in ZrSiS can be understood by electron-hole compensation and the open orbital of Fermi surface. Because of these superior MR properties, ZrSiS may be used in the novel magnetic sensors.
75 citations
TL;DR: In this paper, the authors reported the observation of colossal positive magnetoresistance (MR) in single crystalline, high mobility TaAs2 semimetal, and the excellent fit of MR by a single quadratic function of the magnetic field B over a wide temperature range suggests the semiclassical nature of the MR.
Abstract: We report the observation of colossal positive magnetoresistance (MR) in single crystalline, high mobility TaAs2 semimetal. The excellent fit of MR by a single quadratic function of the magnetic field B over a wide temperature range (T = 2–300 K) suggests the semiclassical nature of the MR. The measurements of Hall effect and Shubnikov-de Haas oscillations, as well as band structure calculations, suggest that the giant MR originates from the nearly perfectly compensated electrons and holes in TaAs2. The quadratic MR can even exceed 1 200 000% at B = 9 T and T = 2 K, which is one of the largest values among those of all known semi-metallic compounds, including the very recently discovered WTe2 and NbSb2. The giant positive magnetoresistance in TaAs2 not only has a fundamentally different origin from the negative colossal MR observed in magnetic systems but also provides a nice complemental system that will be beneficial for applications in magnetoelectronic devices.
64 citations
TL;DR: The direct experimental evidence of WL in QIEs observed in the single-crystal La0.7Sr0.3MnO3 (LSMO) ultrathin films deposited by laser molecular beam epitaxy convincingly leads to the solid conclusion that the resistivity minima at low temperatures in single- Crystal manganites are attributed to both the e-e interaction and the WL effect.
Abstract: Quantum interference effects (QIEs) dominate the appearance of low-temperature resistivity minimum in colossal magnetoresistance manganites. The T1/2 dependent resistivity under high magnetic field has been evidenced as electron-electron (e-e) interaction. However, the evidence of the other source of QIEs, weak localization (WL), still remains insufficient in manganites. Here we report on the direct experimental evidence of WL in QIEs observed in the single-crystal La0.7Sr0.3MnO3 (LSMO) ultrathin films deposited by laser molecular beam epitaxy. The sharp cusps around zero magnetic field in magnetoresistance measurements is unambiguously observed, which corresponds to the WL effect. This convincingly leads to the solid conclusion that the resistivity minima at low temperatures in single-crystal manganites are attributed to both the e-e interaction and the WL effect. Moreover, the temperature-dependent phase-coherence length corroborates the WL effect of LSMO ultrathin films is within a two-dimensional localization theory.
63 citations
TL;DR: This study on several manganite samples illustrates the method of significant enhancement of MR with the reduction of the particle size in nanometer scale and shows the method will have enormous potential for magnetic field sensor technology.
Abstract: The Physics of materials with large magnetoresistance (MR), defined as the percentage change of electrical resistance with the application of external magnetic field, has been an active field of research for quite some times. In addition to the fundamental interest, large MR has widespread application that includes the field of magnetic field sensor technology. New materials with large MR is interesting. However it is more appealing to vast scientific community if a method describe to achieve many fold enhancement of MR of already known materials. Our study on several manganite samples [La1−xCaxMnO3 (x = 0.52, 0.54, 0.55)] illustrates the method of significant enhancement of MR with the reduction of the particle size in nanometer scale. Our experimentally observed results are explained by considering model consisted of a charge ordered antiferromagnetic core and a shell having short range ferromagnetic correlation between the uncompensated surface spins in nanoscale regime. The ferromagnetic fractions obtained theoretically in the nanoparticles has been shown to be in the good agreement with the experimental results. The method of several orders of magnitude improvement of the magnetoresistive property will have enormous potential for magnetic field sensor technology.
53 citations
TL;DR: It is shown that ultrabroadband terahertz pulses can simultaneously trace the ultrafast evolution of coexisting lattice and electronic orders and demonstrates the sort of profound insight that disentangling strongly coupled components of order parameters in the time domain may provide for the understanding of a broad class of phase transitions.
Abstract: The simultaneous ordering of different degrees of freedom in complex materials undergoing spontaneous symmetry-breaking transitions often involves intricate couplings that have remained elusive in phenomena as wide ranging as stripe formation, unconventional superconductivity or colossal magnetoresistance. Ultrafast optical, x-ray and electron pulses can elucidate the microscopic interplay between these orders by probing the electronic and lattice dynamics separately, but a simultaneous direct observation of multiple orders on the femtosecond scale has been challenging. Here we show that ultrabroadband terahertz pulses can simultaneously trace the ultrafast evolution of coexisting lattice and electronic orders. For the example of a charge-density-wave (CDW) in 1T-TiSe2, we demonstrate that two components of the CDW order parameter - excitonic correlations and a periodic lattice distortion (PLD) - respond very differently to 12-fs optical excitation. Even when the excitonic order of the CDW is quenched, the PLD can persist in a coherently excited state. This observation proves that excitonic correlations are not the sole driving force of the CDW transition in 1T-TiSe2, and exemplifies the sort of profound insight that disentangling strongly coupled components of order parameters in the time domain may provide for the understanding of a broad class of phase transitions.
45 citations
TL;DR: In this article, low temperature resistivity and magnetotransport measurements were conducted on pristine and electron doped nickelates (SNO) and they showed that the low temperature transport in both pristine and ionized SNO shows a Mott variable range hopping with a substantial decrease in localization length of carriers by one order in the case of doped samples.
Abstract: We present low temperature resistivity and magnetotransport measurements conducted on pristine and electron doped ${\mathrm{SmNiO}}_{3}$ (SNO). The low temperature transport in both pristine and electron-doped SNO shows a Mott variable range hopping with a substantial decrease in localization length of carriers by one order in the case of doped samples. Undoped SNO films show a negative magnetoresistance (MR) at all temperatures characterized by spin fluctuations with the evolution of a positive cusp at low temperatures. In striking contrast, upon electron doping of the films via hydrogenation, we observe a crossover to a linear nonsaturating positive $\mathrm{MR}\ensuremath{\sim}0.2%$ at 50 K. The results signify the role of localization phenomena in tuning the magnetotransport response in doped nickelates. Ionic doping is therefore a promising approach to tune magnetotransport in correlated perovskites.
42 citations
TL;DR: In this article, the spin-polarized compensated ferrimagnet, Mn2RuxGa, is integrated into MgO-based perpendicular magnetic tunnel junctions.
Abstract: Tunnel magnetoresistance ratios of up to 40% are measured between 10 K and 300 K when the highly spin-polarized compensated ferrimagnet, Mn2RuxGa, is integrated into MgO-based perpendicular magnetic tunnel junctions. Temperature and bias dependences of the tunnel magnetoresistance effect, with a sign change near −0.2 V, reflect the structure of the Mn2RuxGa interface density of states. Despite magnetic moment vanishing at a compensation temperature of 200 K for x≈0.8, the tunnel magnetoresistance ratio remains non-zero throughout the compensation region, demonstrating that the spin-transport is governed by one of the Mn sub-lattices only. Broad temperature range magnetic field immunity of at least 0.5 T is demonstrated in the same sample. The high spin polarization and perpendicular magnetic anisotropy make Mn2RuxGa suitable for applications in both non-volatile magnetic random access memory cells and terahertz spin-transfer oscillators.
TL;DR: In this paper, the authors reported a novel phenomenon, namely giant diamagnetism, induced by electric current in the Mott insulator Ca2RuO4 induced by magnetic field.
Abstract: Mott insulators have surprised us many times by hosting new and diverse quantum phenomena when the 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 a novel phenomenon, namely giant diamagnetism, in the Mott insulator Ca2RuO4 induced by electric current. With application of 1 A/cm2 current, the strongest diamagnetism among all nonsuperconducting materials is induced as the system is tuned to a semimetallic state. The origin lies in the emergence of indirect Dirac cones in the many-body spectrum and associated monopole-like anomaly in the momentum dependent susceptibility. This record-breaking and switchable diamagnetism is a new class of non-equilibrium quantum phenomena on the verge of Mott insulating states.
TL;DR: In this paper, all four types of magnetoresistance correlations can be reproduced in Fe thin films depending on the film thickness, texture, interface, and morphology, and it is inappropriate to use a specific MR angular-dependent correlation as the sole criterion in determining the origin of AMR or ascertaining the exclusive existence of spin Hall MR.
Abstract: Angular-dependent magnetoresistance (MR) is considered to be intrinsic to spintronic materials, represented by the classical anisotropic MR (AMR) phenomenon and the recently emerged spin Hall MR (SMR). So far, isotropic AMR, AMR with geometric size effect and interfacial effect, and SMR have been treated separately to explain distinct MR correlations observed in various systems. Current study shows all four types of MR correlations can be reproduced in Fe thin films depending on the film thickness, texture, interface, and morphology. Results suggest previous explanations of the thin-film MR correlations are incomplete and it is inappropriate to use a specific MR angular-dependent correlation as the sole criterion in determining the origin of AMR or ascertaining the exclusive existence of SMR.
TL;DR: In this paper, it was shown that single-molecule junctions based on nickel electrodes and benzene molecules can yield a significant anisotropic magnetoresistance of up to ∼200% near the conductance quantum G0.
Abstract: Molecular junctions based on ferromagnetic electrodes allow the study of electronic spin transport near the limit of spintronics miniaturization. However, these junctions reveal moderate magnetoresistance that is sensitive to the orbital structure at their ferromagnet–molecule interfaces. The key structural parameters that should be controlled in order to gain high magnetoresistance have not been established, despite their importance for efficient manipulation of spin transport at the nanoscale. Here, we show that single-molecule junctions based on nickel electrodes and benzene molecules can yield a significant anisotropic magnetoresistance of up to ∼200% near the conductance quantum G0. The measured magnetoresistance is mechanically tuned by changing the distance between the electrodes, revealing a nonmonotonic response to junction elongation. These findings are ascribed with the aid of first-principles calculations to variations in the metal–molecule orientation that can be adjusted to obtain highly spi...
TL;DR: In this paper, the authors investigated the atomic scale electronic structure of 1T-TaS2 Mott insulator and its evolution to the metallic state upon isovalent substitution of S with Se.
Abstract: The vicinity of a Mott insulating phase has constantly been a fertile ground for finding exotic quantum states, most notably the high Tc cuprates and colossal magnetoresistance manganites. The layered transition metal dichalcogenide 1T-TaS2 represents another intriguing example, in which the Mott insulator phase is intimately entangled with a series of complex charge-density-wave (CDW) orders. More interestingly, it has been recently found that 1T-TaS2 undergoes a Mott-insulator-to-superconductor transition induced by high pressure, charge doping, or isovalent substitution. The nature of the Mott insulator phase and transition mechanism to the conducting state is still under heated debate. Here, by combining scanning tunneling microscopy (STM) measurements and first-principles calculations, we investigate the atomic scale electronic structure of 1T-TaS2 Mott insulator and its evolution to the metallic state upon isovalent substitution of S with Se. We identify two distinct types of orbital textures - one localized and the other extended - and demonstrates that the interplay between them is the key factor that determines the electronic structure. Especially, we show that the continuous evolution of the charge gap visualized by STM is due to the immersion of the localized-orbital-induced Hubbard bands into the extended-orbital-spanned Fermi sea, featuring a unique evolution from a Mott gap to a charge-transfer gap. This new mechanism of orbital-driven Mottness collapse revealed here suggests an interesting route for creating novel electronic state and designing future electronic devices.
TL;DR: This study provides a model approach to search for CMR systems other than manganites, such as Mott insulators in the vicinity of the boundary between competing phases, with important implications because a magnetic field usually stabilizes the insulating ground state in a Mott-Hubbard system.
Abstract: We present a new type of colossal magnetoresistance (CMR) arising from an anomalous collapse of the Mott insulating state via a modest magnetic field in a bilayer ruthenate, Ti-doped ${\mathrm{Ca}}_{3}{\mathrm{Ru}}_{2}{\mathrm{O}}_{7}$. Such an insulator-metal transition is accompanied by changes in both lattice and magnetic structures. Our findings have important implications because a magnetic field usually stabilizes the insulating ground state in a Mott-Hubbard system, thus calling for a deeper theoretical study to reexamine the magnetic field tuning of Mott systems with magnetic and electronic instabilities and spin-lattice-charge coupling. This study further provides a model approach to search for CMR systems other than manganites, such as Mott insulators in the vicinity of the boundary between competing phases.
TL;DR: In this article, the detailed magnetic, magnetoelectric (ME), magnetodielectric and thermal expansion properties in Co4Nb2O9 crystal were investigated, and a magnetic-field-induced spin flop was observed below antiferromagnetic (AFM) transition temperature TN.
Abstract: We have investigated the detailed magnetic, magnetoelectric (ME), magnetodielectric (MD) and thermal expansion properties in Co4Nb2O9 crystal. A magnetic-field-induced spin flop was observed below antiferromagnetic (AFM) transition temperature TN. Dielectric constant at applied magnetic field nearly diverges around the AFM transition, giving rise to a colossal MD effect as high as ∼138% around TN. Theoretical analysis of the ME and MD data revealed a major contribution of critical spin fluctuation to the colossal MD effect in Co4Nb2O9. These results suggest that linear ME materials with large ME coupling might be potentially used to realize large MD effect for future application.
TL;DR: The solution-processed composite films show enhanced low-field magnetoresistance effect which are crucial in practical applications and are expected to pave the pathway in the field of hole-doped perovskites with their intrinsic colossal magnetores resistance.
Abstract: Polymer-assisted deposition method has been used to fabricate self-assembled epitaxial La0.67Ca0.33MnO3:NiO and La0.67Ca0.33MnO3:Co3O4 films on LaAlO3 substrates. Compared to pulsed-laser deposition method, polymer-assisted deposition provides a simpler and lower-cost approach to self-assembled composite films with enhanced low-field magnetoresistance effect. After the addition of NiO or Co3O4, triangular NiO and tetrahedral Co3O4 nanoparticles remain on the surface of La0.67Ca0.33MnO3 films. This results in a dramatic increase in resistivity of the films from 0.0061 Ω•cm to 0.59 Ω•cm and 1.07 Ω•cm, and a decrease in metal-insulator transition temperature from 270 K to 180 K and 172 K by the addition of 10%-NiO and 10%-Co3O4, respectively. Accordingly, the maximum absolute magnetoresistance value is improved from −44.6% to −59.1% and −52.7% by the addition of 10%-NiO and 10%-Co3O4, respectively. The enhanced low-field magnetoresistance property is ascribed to the introduced insulating phase at the grain boundaries. The magnetism is found to be more suppressed for the La0.67Ca0.33MnO3:Co3O4 composite films than the La0.67Ca0.33MnO3:NiO films, which can be attributed to the antiferromagnetic properties of the Co3O4 phase. The solution-processed composite films show enhanced low-field magnetoresistance effect which are crucial in practical applications. We expect our polymer-assisted deposited films paving the pathway in the field of hole-doped perovskites with their intrinsic colossal magnetoresistance.
TL;DR: In this paper, focused ion beam (FIB) technology was applied to deposit Pt electrodes on the WS2 flakes, and the FIB-deposited contacts exhibited linear electrical characteristics.
Abstract: The discovery of graphene ignited intensive investigation of two-dimensional materials. A typical two-dimensional material, transition metal dichalcogenide (TMDC), attracts much attention because of its excellent performance in field effect transistor measurements and applications. Particularly, when TMDC reaches the dimension of a few layers, a wide range of electronic and optical properties can be detected that are in striking contrast to bulk samples. In this letter, we synthesized WS2 single-crystal nanoflakes using physical vapor deposition and carried out a series of measurements of the contact resistance and magnetoresistance. Focused ion beam (FIB) technology was applied to deposit Pt electrodes on the WS2 flakes, and the FIB-deposited contacts exhibited linear electrical characteristics. Resistance versus temperature measurements showed similar Mott variable range hopping behavior in different magnetic fields. Additionally, a temperature-modulated negative-to-positive magnetoresistance transition...
TL;DR: In this paper, the authors use first-principles theory to predict that the application of uniaxial compressive strain leads to a transition from an antiferromagnetic insulator to a ferromagnetic half-metal phase in ${\mathrm{LaMnO}}_{3}$.
Abstract: We use first-principles theory to predict that the application of uniaxial compressive strain leads to a transition from an antiferromagnetic insulator to a ferromagnetic half-metal phase in ${\mathrm{LaMnO}}_{3}$. We identify the Q2 Jahn-Teller mode as the primary mechanism that drives the transition, indicating that this mode can be used to tune the lattice, charge, and spin coupling. Applying $\ensuremath{\simeq}6$ GPa of uniaxial pressure along the [010] direction activates the transition to a half-metallic $\mathit{pseudocubic}$ state. The half-metallicity opens the possibility of producing colossal magnetoresistance in the stoichiometric ${\mathrm{LaMnO}}_{3}$ compound at significantly lower pressure compared to recently observed investigations using hydrostatic pressure.
TL;DR: In this article, the effects of strain on the electronic structure of a heteroepitaxial thin film of a topological crystalline insulator, SnTe, have been investigated using scanning tunneling microscopy and quasiparticle interference imaging.
Abstract: Orbital degrees of freedom can have pronounced effects on the fundamental properties of electrons in solids. In addition to influencing bandwidths, gaps, correlation strength and dispersion, orbital effects have also been implicated in generating novel electronic and structural phases, such as Jahn-Teller effect and colossal magnetoresistance. In this work, we show for the first time how the orbital nature of bands can result in non-trivial effects of strain on the band structure. We use scanning tunneling microscopy and quasiparticle interference imaging to study the effects of strain on the electronic structure of a heteroepitaxial thin film of a topological crystalline insulator, SnTe. We find a surprising effect where strain applied in one direction affects the band structure in the perpendicular direction. Our theoretical calculations indicate that this effect directly arises from the orbital nature of the conduction and valance bands. Our results imply that a microscopic model capturing strain effects on the band structure must include a consideration of the orbital nature of the bands.
TL;DR: This work could provide important insights into the mechanisms that govern magnetotransport in dilute magnetic oxides, and it also demonstrated an effective approach to manipulating magnetoresistance in these materials that have important spintronic applications.
Abstract: We report magnetoresistance (MR) manipulation and sign reversal induced by carrier concentration modulation in Mn-doped ZnO nanowires. At low temperatures positive magnetoresistance was initially observed. When the carrier concentration was increased through the application of a gate voltage, the magnetoresistance also increased and reached a maximum value. However, further increasing the carrier concentration caused the MR to decrease, and eventually an MR sign reversal from positive to negative was observed. An MR change from a maximum positive value of 25% to a minimum negative value of 7% was observed at 5 K and 50 KOe. The observed MR behavior was modeled by considering combined effects of quantum correction to carrier conductivity and bound magnetic polarons. This work could provide important insights into the mechanisms that govern magnetotransport in dilute magnetic oxides, and it also demonstrated an effective approach to manipulating magnetoresistance in these materials that have important spintronic applications.
TL;DR: In this article, the authors investigated tunneling magnetoresistance (TMR) phenomena in hybrid Fe/GaAlAs/GaMnAs magnetic tunnel junctions (MTJ) by rotating a magnetic field of constant strength in the film plane.
Abstract: Tunneling magnetoresistance (TMR) phenomena in hybrid Fe/GaAlAs/GaMnAs magnetic tunnel junctions (MTJs) were investigated by rotating a magnetic field of constant strength in the film plane. When a strong field (e.g., 4000 G) is used, the magnetization in GaMnAs and Fe coherently rotates in both layers, resulting in a smooth angular dependence of TMR. In contrast, abrupt transition steps and plateaus are observed in TMR, when a weak field (below 100 G) is rotated. The behavior observed in strong fields is ascribed to tunneling anisotropic magnetoresistance, an effect that occurs when magnetizations in both magnetic layers in the MTJ are aligned parallel to each other. The tunneling behavior observed in weak fields, on the other hand, is caused by differences in relative magnetization alignments in the two layers that arise from differences in their magnetocrystalline anisotropies. The latter behavior provided the anisotropic TMR that involved with parallel and antiparallel alignments at specific crystallographic directions.
TL;DR: In this paper, the authors reported the large positive non-saturating linear magnetoresistance in topological crystalline insulator, Pb0.6Sn0.4Te, at different temperatures between 3 K and 300 K in magnetic field up to 9 T.
TL;DR: In this article, the interfacial reaction between ferromagnetic (FM) Pr 0.7 Sr 0.3 MnO 3 (PSMO-3) in proximity to charge ordered (CO) La 0.5 Ca 0.
TL;DR: In this article, a crossover from the semiclassical parabolic field dependent magnetoresistance to linear field dependent magnetic susceptibility with increasing magnetic field was observed, which can be described very well by combining the cyclotron contribution and the quantum limit magnetoreduction behavior.
Abstract: We report the large linear magnetoresistance ($\sim 300\%$ in 9 T field at 2 K) and magnetothermopower in layered SrZnSb$_2$ crystal with quasi-two-dimensional Sb layers. A crossover from the semiclassical parabolic field dependent magnetoresistance to linear field dependent magnetoresistance with increasing magnetic field is observed. The magnetoresistance behavior can be described very well by combining the semiclassical cyclotron contribution and the quantum limit magnetoresistance. Magnetic field also enhances the thermopower. Our results can be well understood by the magnetotransport of Dirac states in the bulk band structure.
TL;DR: In order to reveal the many-body interactions in three-dimensional perovskite manganites that show colossal magnetoresistance, an in-situ angle-resolved photoemission spectroscopy was performed on La_{0.6}Sr{0.4}MnO_{3} and investigated the behavior of quasiparticles.
Abstract: In order to reveal the many-body interactions in three-dimensional perovskite manganites that show colossal magnetoresistance, we performed an in situ angle-resolved photoemission spectroscopy on La_{0.6}Sr_{0.4}MnO_{3} and investigated the behavior of quasiparticles. We observed quasiparticle peaks near the Fermi momentum in both the electron and the hole bands, and clear kinks throughout the entire hole Fermi surface in the band dispersion. This isotropic behavior of quasiparticles and kinks suggests that polaronic quasiparticles produced by the coupling of electrons with Jahn-Teller phonons play an important role in the colossal magnetoresistance properties of the ferromagnetic metallic phase of three-dimensional manganites.
TL;DR: In this article, structural, magnetic, electrical and magnetoresistive properties of La0.7Ca0.3 thin films epitaxially grown on LaAlO3 single crystalline substrates using metal organic deposition process were investigated using X-ray diffraction measurements.
07 Dec 2016
TL;DR: In this article, a self-assembled nanocrystalline NiCo2O4, a spinel cobaltite material, was reported to have low-field magnetoresistance as large as -19.1% at 0.5 T and -50% at 9 T (2 K).
Abstract: Low-field magnetoresistance is an effective and energy-saving way to use half-metallic materials in magnetic reading heads and magnetic random access memory. Common spin-polarized materials with low field magnetoresistance effect are perovskite-type manganese, cobalt, and molybdenum oxides. In this study, we report a new type of spinel cobaltite materials, self-assembled nanocrystalline NiCo2O4, which shows large low field magnetoresistance as large as –19.1% at 0.5 T and –50% at 9 T (2 K). The large low field magnetoresistance is attributed to the fast magnetization rotation of the core nanocrystals. The surface spin-glass is responsible for the observed weak saturation of magnetoresistance under high fields. Our calculation demonstrates that the half-metallicity of NiCo2O4 comes from the hopping eg electrons within the tetrahedral Co-atoms and the octahedral Ni-atoms. The discovery of large low-field magnetoresistance in simple spinel oxide NiCo2O4, a non-perovskite oxide, leads to an extended family of low-field magnetoresistance materials. (© 2016 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)