arXiv subjects

Masaaki Tanaka

Publications and source records attributed to Masaaki Tanaka.

At least 19 recordsLinked to original sources

arXiv2026

Orientation selection and superconducting properties of epitaxial Al on ferromagnetic semiconductor (In,Fe)As

Superconductor/ferromagnet heterostructures provide a versatile platform for exploring spin-dependent superconducting phenomena arising from interfacial proximity effects. In this article, we investigate the structural and superconducting properties of Al thin films grown in situ by molecular beam epitaxy on strained Fe-doped ferromagnetic semiconductor (FMS) (In,Fe)As layers. X-ray diffraction and transmission electron microscopy reveal the epitaxial growth of single-crystalline Al layers, with the growth orientation changing from (110) to (111) as the in-plane lattice constant of (In,Fe)As increases. The superconducting critical temperature of Al varies systematically with the film surface morphology and grain size. In addition, the critical magnetic field of Al exhibits an anomalous decrease below 0.5 K, possibly reflecting magnetic coupling to the underlying FMS (In,Fe)As layer. These findings provide a guideline for material design of epitaxial Al/(In,Fe)As heterostructures, which may serve as a promising platform for investigating proximity-induced superconducting and magnetic phenomena in semiconductor-based hybrid quantum devices.

cond-mat.supr-con↗

arXiv2026

Spin-related transport in a polycrystalline NiCo2O4 film: Drastic current-induced change in resistivity-temperature characteristics via spin injection

We have studied spin-related transport in a polycrystalline NiCo2O4 (NCO) film on a MgAl2O4/Si(001) substrate, motivated by potential applications of the theoretical half-metallicity of NCO to Si-based high-performance spin-transport devices. Our approach is to systematically measure and analyze the temperature dependence of the film's resistivity ($ρ-T$) with various in-plane currents (100 nA$-$1 mA) and temperatures (4$-$290 K). With increasing current, the $ρ-T$ curve changes drastically from semiconducting ($dρ/dT<0$) to non-monotonic and eventually toward metallic ($dρ/dT>0$). A distinctive feature is that the single NCO film exhibits a $ρ-T$ characteristic of polycrystalline defective NCO at 100 nA, whereas it exhibits a $ρ-T$ characteristic of epitaxial less-defective NCO over a wide temperature range at 1 mA. This current-induced evolution of $ρ-T$ reflects the enhancement of the Curie temperature of defective regions near grain boundaries, accompanied by enhanced spin alignment there. We proposed a spin-related transport model that extends conventional hopping conduction models by incorporating the temperature- and current-dependent degree of spin alignment, as well as its spatial dependence inherent to polycrystalline NCO. This model comprehensively explains the interplay between the spin-alignment profile and transport mechanism. The analysis reveals that spin injection from grain bodies to grain boundaries enhances the spin alignment there and strengthens double-exchange interactions, facilitating conduction. This phenomenon strongly depends on both temperature and current. Our findings provide evidence of spin-polarized electrons inside the grain bodies, highlighting the potential of our polycrystalline NCO film as an efficient spin source. The present model is further supported by current$-$voltage and magnetoresistance features.

cond-mat.mtrl-sci↗

arXiv2026

Interplay of superconductivity and ferromagnetism in ferromagnetic semiconductor-based Josephson junctions

The interplay between superconductivity and ferromagnetism has long been pursued as a route to unconventional Josephson effects, yet suitable material platforms remain limited. Here we report Josephson junctions based on epitaxial Al/InAs/(Ga,Fe)Sb heterostructures grown by low-temperature molecular beam epitaxy, achieving atomically abrupt superconductor/semiconductor/ferromagnetic interfaces. The devices exhibit clear proximity-induced superconductivity, including multiple Andreev reflections and gate-tunable supercurrents, confirming transparent coupling across the hybrid structure. Under perpendicular magnetic fields, the junctions reveal highly unconventional Fraunhofer interference patterns with hysteresis, flux jumps, asymmetric lobe evolution, and clear nonreciprocity, providing strong evidence of induced ferromagnetism and broken time-reversal symmetry in the superconducting channel. Gate control further modulates the critical current, highlighting the semiconducting nature of the system. Our results demonstrate that ferromagnetic semiconductor heterostructures can serve as a highly tunable platform for exploring proximity-induced superconductivity and superconducting diode effects, and for advancing device concepts at the intersection of magnetism and quantum electronics.

cond-mat.supr-con↗

arXiv2026

Intrinsic low-spin state and strain-tunable anomalous Hall scaling in high-quality SrRuO3 (111) films

The (111)-oriented 4d ferromagnetic perovskite SrRuO3 (SRO) offers a unique triangular-lattice geometry, making it a promising platform for exploring Berry-curvature-driven and spin-orbit-coupled transport. Here, we present a systematic study of the structure, magnetism, and magnetotransport of high-quality SRO (111) thin films with thicknesses t = 1.2-60 nm grown on SrTiO3 (111) substrates by machine-learning-assisted molecular beam epitaxy. We achieved a residual resistivity ratio of 45.5 in a 60 nm-thick film, the highest reported for this orientation, enabling access to intrinsic electronic and magnetic behavior. Temperature-dependent resistivity confirms Fermi-liquid transport below 15 K in both coherently strained (t = 10, 20 nm) and strain-relaxed (t = 60 nm) films, thereby enabling detailed magnetotransport and magnetic measurements. The linear, non-saturating positive magnetoresistance persists up to 14 T, while Hall-effect measurements and temperature scaling separate intrinsic (Karplus-Luttinger) and extrinsic (side-jump) contributions to the anomalous Hall effect, with the relative weight tuned by (111) epitaxial strain. X-ray magnetic circular dichroism at the Ru M2,3 and O K edges, together with SQUID magnetometry, demonstrates an intrinsically low-spin Ru ground state for both coherently strained and relaxed films, resolving ambiguities among prior reports. These detailed crystalline, electrical, and magnetic characterizations provide a rigorous foundation for understanding and engineering quantum transport in SRO (111).

cond-mat.mtrl-sci↗

arXiv2026

Epitaxial lift-off of La$_{2/3}$Sr$_{1/3}$MnO$_3$ membranes enabled by BaO sacrificial layers and restoration of the Curie temperature

Ultrathin complex-oxide membranes provide a powerful platform for strain engineering, interfacial control, and heterogeneous integration; however, their formation remains constrained by the availability and performance of suitable water-soluble sacrificial layers. This letter demonstrates that barium oxide (BaO) serves as a highly efficient and rapidly dissolving water-soluble sacrificial layer, enabling the epitaxial lift-off and transfer of ultrathin La$_{2/3}$Sr$_{1/3}$MnO$_3$ (LSMO) membranes onto SiO$_x$/Si substrates. LSMO membranes with a thickness of approximately 8 nm are released using a BaO sacrificial layer grown by molecular beam epitaxy, while high crystallinity is preserved and Ba interdiffusion is limited to a narrow interfacial region of approximately 0.5 nm. Post-transfer oxygen annealing at 600 ${}^\circ$C increases the Curie temperature ($T_C$) from 342 K to 346 K by eliminating Mn$^{2+}$ states associated with oxygen vacancies generated through oxygen extraction into the BaO layer. These results show that BaO provides a fast, scalable, and compositionally simple route for complex-oxide membrane release, while brief oxygen annealing is essential to restore the optimal Mn valence state and achieve the intrinsic high $T_C$.

cond-mat.mtrl-sci↗

arXiv2025

Spin-transport characteristics in a Si-based spin metal-oxide-semiconductor field-effect transistor (spin MOSFET): Bias dependence of the spin polarization in Si and magnetoresistance in spin-valve signals

We have studied the spin transport characteristics of a spin metal-oxide-semiconductor field-effect transistor (spin MOSFET), particularly the bias voltage dependence of the electron spin polarization P_S in Si and the magnetoresistance ratio MR in spin-valve signals, to optimize the device performance. The spin MOSFET device has an 8-nm-thick p-Si channel with a back gate (G) and ferromagnetic source / drain (S/D) junctions consisting of Fe/Mg/MgO/SiOx/n+-Si. In addition to transistor characteristics with an on-off ratio of 104, clear spin-valve signals and Hanle spin precession signals were observed at 4 K in a wide range of the source-to-gate V_GS and source-to-drain V_DS bias voltages. We achieved a high P_S of 50% and a high MR of 0.35% as the maximum values in their single-peaked curves plotted as a function of the junction voltage V_J, mainly because the ferromagnetic S/D junction can generate high P_S and the spin diffusion length is very long in the Si inversion channel. These P_S and MR values are the highest ever reported in spin-MOSFETs. Our spin transport model for our spin MOSFET structure was improved in this study by taking into account the electron distribution and band profile of the n+-Si regions in the ferromagnetic S/D junctions, which enables the accurate estimation of P_S. Detailed analyses with various V_GS and V_J clarified that P_S is determined only by V_J. Our analyses also revealed that the main parameters for determining MR, such as P_S and the resistance-area products of the S/D ferromagnetic junctions, have different V_J dependences, leading to the finding that the present device does not exploit the full potential of the ferromagnetic S/D junctions to maximize MR. Based on the results, we discuss the device physics and engineering for further enhancement of MR, with a focus on the electrical and spin-related properties of the ferromagnetic S/D junctions.

cond-mat.mes-hall↗

arXiv2025

Epitaxial growth and transport properties of a metallic altermagnet CrSb on a GaAs (001) substrate

A newly identified class of magnetic materials called altermagnets has attracted much attention due to the practical properties of spin-splitting bands akin to ferromagnets and small compensated magnetization akin to antiferromagnets. These features make them promising candidates for applications in spintronics devices. Among candidate materials, CrSb is promising because of its high ordering temperature (~705 K) and large spin-splitting energy; however, it is predicted that tuning the Néel vector requires additional symmetry breaking or a change in the easy magnetization axis. While applying epitaxial strain can modulate the symmetry, the selection of substrates with closely matched lattice constants for heteroepitaxial growth is limited for altermagnets, which generally have low crystal symmetry. Therefore, exploring the heteroepitaxial growth of altermagnet thin films on well-established, dissimilar crystal systems is valuable. (001)-oriented III-V semiconductors, which share group-V elements with the overgrown CrSb, offer an ideal platform because they are expected to have material compatibility with stable interfaces, as well as tunability of the buffer layer's bandgap and lattice constant by varying the atomic composition of their group-III and group-V atoms. In this study, we have achieved the molecular beam epitaxial growth of a CrSb ($\bar{1}10$) thin film on a GaAs (001) substrate by inserting thin FeSb ($\bar{1}10$) / AlAs (001) buffer layers. The in-plane epitaxial relationship is found to be CrSb [110] $\|$ GaAs [110] and CrSb [001] $\|$ GaAs [$\bar{1}10$], and epitaxial strain is also confirmed. We also characterized the magneto-transport properties of the grown CrSb thin film. Although the obtained conductivity tensors are mainly explained by a two-carrier model, not by an anomalous Hall effect, this model reveals the presence of high-mobility electron and hole carriers.

cond-mat.mtrl-sci↗

arXiv2025

Giant odd-parity magnetoresistance from proximity-induced topological states

Magnetoresistance typically exhibits even symmetry with respect to the magnetic field, owing to time reversal symmetry (TRS) as dictated by Onsager reciprocity relations. However, in certain systems where TRS is broken, magnetoresistance may acquire an odd component with respect to the magnetic field, referred to as odd parity magnetoresistance (OMR). To date, reported OMR values have been modest, usually restricted to a few tens of percent even under high magnetic fields. Here, we report the discovery of a giant OMR reaching up to 1,150% under a relatively low field of 1 T in a heterostructure composed of 3 nm thick alpha Sn and a ferromagnetic semiconductor, (In,Fe)Sb. Although alpha Sn in this thickness range is a trivial narrow gap semiconductor, analysis of Shubnikov de Haas oscillations combined with ab initio calculations reveals the emergence of tilted topological surface states, induced via magnetic proximity from the (In,Fe)Sb layer. The observed OMR behavior is well explained by a Boltzmann transport model assuming the presence of oppositely tilted Weyl cones in the alpha Sn band structure. Our findings not only shed new light on the physics of OMR but also suggest promising avenues for its application in electronic and spintronic devices, such as ultrasensitive magnetic sensors.

cond-mat.mtrl-sci↗

arXiv2025

Giant Spin-to-Charge Conversion by Tailoring Magnetically Proximitized Topological Dirac Semimetal

While ferromagnet and topological material bilayers are widely studied to obtain efficient spin charge conversion via topological surface states (TSS), the influence of the magnetic proximity effect (MPE) on the TSS evolution and conversion efficiency remains poorly understood. In this study, we experimentally probe and reveal the behavior of spin momentum locked TSS through spin pumping measurements in heterostructures composed of ferromagnetic Fe and the topological Dirac semimetal alpha Sn. As the alpha Sn thickness (tSn) increases from 9 to 35 nm, the Gilbert damping constant of the Fe layer exhibits a pronounced peak at tSn = 25 nm, followed by a decrease at greater thicknesses. Our rigorous theoretical analysis, combining analytical modeling and first principles calculations, attributes this behavior to the TSS disappearance at the Fe and alpha Sn interface and exchange gap opening on the opposite surface, both induced by the long range MPE and its influence on the spin charge conversion efficiency. At tSn = 25 nm, we demonstrate highly efficient spin charge conversion with an inverse Edelstein length of 3.14 nm, the highest value reported at room temperature for ferromagnet and topological material bilayers. These findings underscore the critical role of tuning TSS properties under MPE for advancing topological materials in spintronic applications.

cond-mat.mtrl-sci↗

arXiv2025

Spin injection in Si-based ferromagnetic tunnel junctions with MgO/MgAl2O4 barriers:Experimental and theoretical investigation of barrier thickness-dependent spin tunneling efficiency

We have experimentally and theoretically investigated the spin transport in Fe/Mg/MgO/MgAl2O4/n+-Si(001) ferromagnetic tunnel junctions on a Si substrate, by systematically varying the thickness combination of amorphous MgO and MgAl2O4 tunnel barrier layers with a sliding shutter between the evaporation sources and substrate during electron-beam evaporation. A technical advantage of MgAl2O4 is that a continuous and flat thin film is realized on a Si substrate even when the MgAl2O4 thickness is as thin as 0.5 nm, unlike MgO, which enables us to examine the spin transport in a thinner range of the tunnel barrier thickness. Our distinct finding is as follows: When the Fe/Mg/MgO interface is used on the top side, the spin polarization PS of tunneling electrons increases at 10 K as the total MgO/MgAl2O4 tunnel barrier thickness (tox = 0.47 - 1.4 nm) is increased, regardless of different thickness combinations, and PS shows saturation-like behavior when tox is above 1.1 nm. Since this feature cannot be explained by the well-known conductivity mismatch in semiconductor-based ferromagnetic tunnel junctions, we propose a simple phenomenological tunneling model based on two different direct tunneling paths, which have higher/lower spin polarizations with longer/shorter decay lengths. Our numerical calculation reproduces the relationship between the spin polarization PS and total tunnel barrier thickness tox in the experiments, indicating that the dominant mechanism is an increasing contribution of the lower spin polarization path as tox is decreased. We discuss possible origins for this phenomenon including intrinsic and extrinsic tunneling mechanisms. Our analysis method provides an insight into the detailed spin transport physics in semiconductor-based ferromagnetic junctions, particularly, with a very thin tunnel barrier layer.

physics.app-ph↗

arXiv2025

Topological surface states induced by the magnetic proximity effect

The combination of magnetism and topological properties in one material platform is attracting significant attention due to the potential of realizing low power consumption and error-robust electronic devices. Common practice is to start from a topological material with band inversion and incorporates ferromagnetism via chemical doping or magnetic proximity effect (MPE). In this work, we show that a topological material is not necessary and that both ferromagnetism and band inversion can be established simultaneously in a trivial insulating material by MPE from a neighbouring ferromagnetic layer. This novel route is demonstrated using quantum transport measurements and first principles calculations in a heterostructure consisting of 5 nm thick FeOx/1 monolayer of FeAs/ 3 nm thick alpha Sn. The Shubnikov de Haas oscillations show that there is linear band dispersion with high mobility in the heterostructure even though a 3 nm thick alpha Sn single layer is a trivial semiconductor. Furthermore, first principles calculations reveal that band inversion indeed occurs in this heterostructure, suggesting that the observed linear band is a topological surface state within this inverted gap. This work significantly expands the foundation for realizing magnetic topological materials in a myriad of trivial narrow gap semiconductors.

cond-mat.mtrl-sci↗

arXiv2025

Magnetic anisotropy related to hybridization between Fe 3$d$ and As 4$p$ orbitals in a bcc Fe-As thin film

The magnetic anisotropy (MA) of Fe-based ferromagnetic thin films has been extensively studied for device applications. The examined material is a new Fe-based ferromagnetic thin film, bcc Fe$_{1-x}$As$_x$ (Fe-As) with the in-plane MA (IMA) grown on a GaAs (111)B substrate. The magnetic properties of the Fe-As thin film have been investigated by Xray magnetic circular dichroism (XMCD) and magnetic circular dichroism in hard X-ray photoemission spectroscopy (MCD-HAXPES) to elucidate the role of As ions in the IMA. The XMCD spectra at the Fe $L_{2,3}$ edge and MCD-HAXPES spectra of the Fe 2$p$ core level exhibit ferromagnetic and metallic features like Fe metal. The XMCD at the As $L_{2,3}$ edge demonstrates that the As ions contribute to the ferromagnetism of bcc Fe-As through the hybridization between the Fe 3$d$ and As 4$p$ orbitals. The estimations of the magnetic moments of Fe using the XMCD sum rules have revealed that the orbital magnetic moment is isotropic and the magnetic dipole term is anisotropic. The anisotropy of the magnetic dipole term can be attributed to the anisotropic $p-d$ hybridization due to epitaxial strain, contributing to the IMA of bcc Fe-As. Our findings enlighten the mechanism of the MA of the non-magnetic ion-doped bcc Fe thin film, which can be applied to other magnetic 3$d$ transition metal thin films doped with non-magnetic elements.

cond-mat.mtrl-sci↗

arXiv2024

Giant memory function based on the magnetic field history of resistive switching under a constant bias voltage

Memristors, which are characterized by their unique input-voltage-history-dependent resistance, have garnered significant attention for the exploration of next-generation in-memory computing, reconfigurable logic circuits, and neural networks. Memristors are controlled by the applied input voltage; however, the latent potential of their magnetic field sensitivity for spintronics applications has rarely been explored. In particular, valuable functionalities are expected to be yielded by combining their history dependence and magnetic field response. Here, for the first time, we reveal a giant memory function based on the magnetic field history of memristive switching, with an extremely large magnetoresistance ratio of up to 32,900% under a constant bias voltage, using a two-terminal Ge-channel device with Fe/MgO electrodes. We attribute this behavior to colossal magnetoresistive switching induced by the d0 ferromagnetism of Mg vacancies in the MgO layers and impact ionization breakdown in the Ge substrate. Our findings may lead to the development of highly sensitive multi-field sensors, high-performance magnetic memory, and advanced neuromorphic devices.

physics.app-ph↗

arXiv2024

Single-layer spin-orbit-torque magnetization switching due to spin Berry curvature generated by minute spontaneous atomic displacement in a Weyl oxide

Spin Berry curvature characterizes the band topology as the spin counterpart of Berry curvature and is crucial in generating novel spintronics functionalities. By breaking the crystalline inversion symmetry, the spin Berry curvature is expected to be significantly enhanced; this enhancement will increase the intrinsic spin Hall effect in ferromagnetic materials and, thus, the spin-orbit torques (SOTs). However, this intriguing approach has not been applied to devices; generally, the extrinsic spin Hall effect in ferromagnet/heavy-metal bilayer is used for SOT magnetization switching. Here, SOT-induced partial magnetization switching is demonstrated in a single layer of a single-crystalline Weyl oxide SrRuO3 (SRO) with a small current density of ~3.1{\times}10^6 A cm-2. Detailed analysis of the crystal structure in the seemingly perfect periodic lattice of the SRO film reveals barely discernible oxygen octahedral rotations with angles of ~5° near the interface with a substrate. Tight-binding calculations indicate that a large spin Hall conductivity is induced around small gaps generated at band crossings by the synergy of inherent spin-orbit coupling and band inversion due to the rotations, causing magnetization reversal. Our results indicate that a minute atomic displacement in single-crystal films can induce strong intrinsic SOTs that are useful for spin-orbitronics devices.

cond-mat.mtrl-sci↗

arXiv2024

Influence of Ru composition deviation from stoichiometry on intrinsic spin-to-charge conversion in SrRuO3

Interconversion between charge and spin currents is a key phenomenon in realizing next-generation spintronic devices. Highly efficient spin-charge interconversion is expected to occur at band crossing points in materials with large spin-orbit interactions due to enhanced spin Berry curvature. On the other hand, if defects and/or impurities are present, they affect the electronic band structure, which in turn reduces the spin Berry curvature. Although defects and impurities are generally numerous in materials, their influence on the spin Berry curvature and, consequently, spin-charge interconversion has often been overlooked. In this paper, we perform spin-pumping experiments for stoichiometric SrRuO3 and non-stoichiometric SrRu0.7O3 films at 300 K, where the films are in paramagnetic states, to examine how Ru composition deviation from the stoichiometric condition influences the spin-to-charge conversion, showing that SrRuO3 has a larger spin Hall angle than SrRu0.7O3. We derive the band structures of paramagnetic SrRuO3 and SrRu0.75O3 using first-principles calculations, indicating that the spin Hall conductivity originating from the spin Berry curvature decreases when the Ru deficiency is incorporated, which agrees with the experimental results. Our results suggest that point-defect- and impurity control is essential to fully exploit the intrinsic spin Berry curvature and large spin-charge interconversion function of materials. These insights help us with material designs for efficient spin-charge interconversions.

cond-mat.mtrl-sci↗

arXiv2024

Correlated Ligand Electrons in the Transition-Metal Oxide SrRuO$_3$

In transition-metal compounds, the transition-metal d electrons play an important role in their physical properties; however, the effects of the electron correlation between the ligand p electrons have not been clear yet. In this Letter, the Ru 4d and O 2p partial density of states (PDOS) in transition-metal oxide SrRuO$_3$ involving Weyl fermions are investigated by resonant photoemission spectroscopy. The observations demonstrate that the O 2p PDOS is distorted from that predicted by first-principles calculations than the Ru 4d PDOS. The results indicate that the electron correlation in the ligand orbitals will be important to understand the electronic structure of the p-d hybridized state in strongly correlated electron systems, even with topological states.

cond-mat.str-el↗

arXiv2024

Identification of electronic dimensionality reduction in semiconductor quantum well structures

Two-dimensional (2D) systems, such as high-temperature superconductors, surface states of topological insulators, and layered materials, have been intensively studied using vacuum-ultraviolet (VUV) angle-resolved photoemission spectroscopy (ARPES). In semiconductor films (heterostructures), quantum well (QW) states arise due to electron/hole accumulations at the surface (interface). The quantized states due to quantum confinement can be observed by VUV-ARPES, while the periodic intensity modulations along the surface normal (kz) direction of these quantized states are also observable by varying incident photon energy, resembling three-dimensional (3D) band dispersion. We have conducted soft X-ray (SX) ARPES measurements on thick and ultrathin III-V semiconductor InSb(001) films to investigate the electronic dimensionality reduction in semiconductor QWs. In addition to the dissipation of the kz dispersion, the SX-ARPES observations demonstrate the changes of the symmetry and periodicity of the Brillouin zone in the ultrathin film as 2D QW compared with these of the 3D bulk one, indicating the electronic dimensionality reduction of the 3D bulk band dispersion caused by the quantum confinement. The results provide a critical diagnosis using SX-ARPES for the dimensionality reduction in semiconductor QW structures.

cond-mat.mtrl-sci↗

arXiv2024

Spin injection and detection in a Si-based ferromagnetic tunnel junction: A theoretical model based on the band diagram and experimental demonstration

We have experimentally and theoretically investigated the spin injection/detection polarization in a Si-based ferromagnetic tunnel junction with an amorphous MgO layer, and demonstrated that the experimental features of the spin polarization in a wide bias range can be well explained using our theoretical model based on the band diagram of the junction and the direct tunneling mechanism. It is shown that the spin polarization originates from the band diagrams of the ferromagnetic Fe layer and n+-Si channel in the junction, while the spin selectivity of the MgO tunnel barrier is not necessary. Besides, we clarified the mechanism of the reduction in spin polarization when the bias is high and nonlinear properties are prominent, where the widely-used spin injection/detection model proposed by Valet and Fert is not applicable. The dominant mechanism of such reduction is found to be spin accumulation saturation (SAS) at the n+-Si interface in contact with the MgO layer as the bias is increased in the spin extraction geometry, which is inevitable in semiconductor-based ferromagnetic tunnel junctions. We performed numerical calculations on a two-terminal spin transport device with a n+-Si channel using the junction properties extracted from the experiments, and revealed that the magnetoresistance (MR) ratio is suppressed mainly by SAS in a higher bias range. Furthermore, we proposed methods for improving the MR ratio in two-terminal spin transport devices. Our experiments and theoretical model provide a deep understanding of the spin injection/detection phenomena in semiconductor-based spin transport devices, toward the realization of high performance under reasonably high bias conditions for practical use.

physics.app-ph↗