High Spin Polarization Research Articles

Mesoporous MnO2 nanosheets for efficient electrocatalytic nitrogen reduction via high spin polarization induced by oxygen vacancy

Mesoporous MnO2 nanosheets for efficient electrocatalytic nitrogen reduction via high spin polarization induced by oxygen vacancy

First-Principles Study of Induced Magnetism in Tungsten Vanadium Selenide Alloys for Spintronic Applications.

The possibility of inducing magnetization in tungsten selenide monolayer by alloying with vanadium selenide was investigated through first-principles calculations. Electronic, optical, and magnetic properties of different W1–xVxSe2 alloy compositions were studied extensively. As the proportion of vanadium atoms in the alloys increased, a phase transition from semiconducting to metallic to semiconducting was discovered. All alloy compositions demonstrated induced magnetism with a long-range ferromagnetic order. Interestingly, in the case of the W0.25V0.75Se2 alloy, spin-up states in the band diagram showed a finite band gap, while a nonzero band gap was found for spin-down states. The W0.25V0.75Se2 alloy can be used as a spin filter tunneling barrier exploiting this fascinating property. High spin polarization of the tunnel current was found for the alloy. Furthermore, under the Curie temperature, electrical conductivity for the spin-up channel was found to be zero, while conductivity for the spin-down channel was around 1019 (Ω cm s)−1 when the chemical potential was 0.2 eV greater than the Fermi energy. Changes in optical properties were also investigated through time-dependent density functional theory calculations. The findings of this study will be beneficial for proposing new magnetic monolayer alloys for application in nanoscale spintronic devices.

Perpendicularly Magnetized MnxGa‐Based Magnetic Tunnel Junctions: Materials, Mechanisms, Performances, and Potential Applications

AbstractMagnetic tunnel junctions (MTJs) exhibit a great profusion of unique functional properties, such as nonvolatility, scalability, high endurance, and low power consumption. For this reason, they have been widely investigated in spin‐based logic and memory devices. Compared with conventional in‐plane MTJs, perpendicular MTJs (pMTJs) enable lower critical switching current and higher integration density. So far, CoFeB/MgO structures with interface‐induced perpendicular magnetic anisotropy (PMA) are the most common ferromagnetic (FM) electrodes in pMTJs, whereas their relatively weak interfacial PMA restricts further development of device nodes. In the past decade, perpendicularly magnetized MnxGa binary alloys, including FM L10‐MnGa and ferrimagnetic D022‐Mn3Ga, have drawn intense attention for serving as a promising magnetic electrode in various MTJ stacking structures because of their large PMA, high spin polarization, and small magnetic damping constant. From an application perspective, MTJs with ultrathin MnxGa electrode show merits in developing high‐density magnetic memory, high‐frequency spin‐torque oscillators, and tunneling magnetoresistance effect‐based high‐field sensors. Herein, the aim is to provide a comprehensive review of recent progress in perpendicularly magnetized MnxGa‐based MTJs. The conclusions and future prospects are also given to inspire more in‐depth research and advance the practical applications.

A first-principles study on the effect of Cr, Mn, and Co substitution on Fe-based normal- and inverse-Heusler compounds: Fe3−xYxZ (x=0, 1, 2, 3; Y= Cr, Mn, Co; Z=Al, Ga, Si)

First-principles calculation has become one of the most reliable approaches in predicting structural, electronic, and magnetic properties for material applications. Alloys in Heusler structures have also attracted much attention recently since they can be easily synthesized and provide interesting properties for future spintronic applications. In this work, we investigate a series of Fe-based Heusler compounds Fe3−xYxZ (x = 0, 1, 2, 3; Y= Cr, Mn, Co; Z= Al, Ga, Si) with L21- and XA-type structures using first-principles calculations based on density functional theory. According to formation energy calculations and mechanical property analysis, most of the studied Heusler compounds are thermodynamically stable and could be synthesized experimentally. The Co substitution leads Fe3−xCoxZ to a ferromagnetic ground state like Fe3Z with a strong magnetization ranging from 4 to 6 μB/f. u. While replacing Fe with Cr or Mn, the exchange coupling between Cr (Mn) and its neighboring atoms generally tend to be anti-parallel. Among the antiferromagnetic compounds, Mn3Al and Mn3Ga are antiferromagnetic half metal while Mn3Si is ferrimagnetic half metal. These rarely found type of half metals with low magnetic moment and high spin polarization at the Fermi level are important for low energy consumption spintronic applications. The estimated Curie temperatures for Mn3Al, and Mn3Si and Co2FeSi (XA) are in good agreement with previously theoretical values, while for Fe3Al and Fe3Si, they are in good agreement with previous experimental results. The good consistency in Curie temperature demonstrates high reliability of our predictions based on first-principles calculations. As for the topological property aspect, we predict Fe2CrAl and Fe2MnAl as the 3-dimensional Weyl semimetal. Furthermore, Fe2CrSi is predicted to be the magnetic nodal-line semimetal. Interestingly, our mechanical property analysis demonstrates that Co3Si and Fe2CoSi (L21) exhibit ultraelastic metal behavior, which is of high potential in advanced mechanical industry. This work suggests that Heusler compounds are excellent candidates for future spintronics as well as for high-performance ultraelastic metals.

Machine learning study of highly spin-polarized Heusler alloys at finite temperature

A huge magnetoresistance (MR) ratio exceeding 2000% at cryogenic temperature that was reported for half-metallic Heusler alloy based magnetic tunnel junctions showed large degradation at room temperature, which impedes practical application of Heusler alloy based MR devices. This motivates us to explore alternative Heusler alloys that show high spin polarization at finite temperatures. Here, we propose half-metallic Heusler alloys based on finite-temperature first-principles calculation via the disordered local moment method together with machine learning. We found several prospective materials at room temperature such as ${\mathrm{Co}}_{2}{\mathrm{MnGa}}_{0.2}{\mathrm{As}}_{0.8}$ and ${\mathrm{Co}}_{2}{\mathrm{FeAl}}_{0.4}{\mathrm{Sn}}_{0.6}$. We also investigated two combinatorial series, ${\mathrm{Co}}_{2}{\mathrm{MnGa}}_{y}{\mathrm{As}}_{1\text{\ensuremath{-}}y}$ and ${\mathrm{Co}}_{2}{\mathrm{FeAl}}_{y}{\mathrm{Sn}}_{1\text{\ensuremath{-}}y}$, to understand the effect of alloy mixing on temperature dependence and found that Fermi level tuning significantly improved the spin polarization and its temperature dependence, especially in ${\mathrm{Co}}_{2}{\mathrm{FeAl}}_{y}{\mathrm{Sn}}_{1\text{\ensuremath{-}}y}$.

Ultralow energy switching with spin polarized magneto-electric properties of co-doped cubic phase BFO: A first-principles study

Bismuth ferrite BiFeO3 (BFO) is one of the most studied multiferroic materials. The coupling between electric polarization and magnetization provides the potential for the next-generation low-switching memory devices. To enhance the switching functionality of BFO, the effect of lanthanum (La) at A-site and cobalt (Co) at B-site as mono- and co-dopants on spin-polarized electronic structure, ferroelectric polarization, and magnetic properties are investigated using the first principles. An increase in the energy states density is observed with the introduction of La and Co atoms, which change the band gap in the spin-down state. La-doping significantly enhances the dielectric constant, whereas the dielectric constant for La and Co co-doped system decreases. Enhancement in the magnetic moment (μB)is detected on introducing Co atoms in BFO as mono- and co-dopant due to the combined involvement of La and Co, which destroy the cycloidal spin structure and activate the hidden spin. The high spin polarization of 87.08 % and linear Edelstein effect of 1.45 ×10–9 m/V are observed in La and Co co-substituted system. The ferroelectric polarization of La and Co co-doped BFO decreased (0.079 C/m2) significantly and has shown ultralow switching energy 0.52 aJ for magneto-electric spin-orbit (MESO) RAM capacitor.

Unconventional Rashba Spin-Orbit Coupling on the Charge Conductance and Spin Polarization of a Ferromagnetic/Insulator/Ferromagnetic Rashba Metal Junction.

A ferromagnetic/insulator/ferromagnetic Rashba metal junction (FM/I/FRM) with both Rashba spin–orbit coupling (RSOC) and exchange energy splitting was studied theoretically. Two kinds of interactions in FRM generate the three metallic states in a FRM; the Rashba ring metal (RRM) state, the anomalous Rashba metal (ARM) state and the normal Rashba metal (NRM) state. The scattering method and the free-electron model are used to describe the transport properties of particles and to calculate the conductance spectrum and the spin polarization of current in the junction. The conductance spectrum in the applied voltage shows the prominent features at the boundaries not only for the three states of the FRM but also in the ARM state. In addition, the conductance in the RRM and ARM states is strongly influenced by both the thickness and barrier height of the insulator layer. We also found that the spin polarization obtains a high value in the ARM state and is not affected by the qualities of the insulator, unlike the RRM and NRM states. Obtaining high-spin polarization from FRM material can be useful to produce spintronic devices in future devices.

High-Efficient Spin Injection in GaN at Room Temperature Through A Van der Waals Tunnelling Barrier

Achieving high-efficient spin injection in semiconductors is critical for developing spintronic devices. Although a tunnel spin injector is typically used, the construction of a high-quality tunnel barrier remains a significant challenge due to the large lattice mismatch between oxides and semiconductors. In this work, van der Waals h-BN films with the atomically flat interface were engaged as the tunnel barrier to achieve high spin polarization in GaN, and the spin injection and transport in GaN were investigated systematically. Based on the Hanle precession and magnetic resistance measurements, CoFeB was determined as an optimal spin polarizer, bilayer h-BN tunnelling barrier was proven to yield a much higher spin polarization than the case of monolayer, and appropriate carrier concentration as well as higher crystal equality of n-GaN could effectively reduce the defect-induced spin scattering to improve the spin transport. The systematic understanding and the high efficiency of spin injection in this work may pave the way to the development of physical connotations and the applications of semiconductor spintronics.

Direct probing of temperature-independent bulk half-metallicity in Co2MnSi by spin-resolved hard x-ray photoemission

We have performed the bulk-sensitive spin-resolved hard x-ray photoelectron spectroscopy (HAXPES) to directly clarify the spin-dependent valence band electronic states and spin polarization of $L{2}_{1}$-ordered ${\mathrm{Co}}_{2}\mathrm{MnSi}$ as a predicted half-metal. The spin-resolved valence band HAXPES spectra clearly exhibited the difference in the majority and minority spin states in the bulk region of a 30-nm-thick ${\mathrm{Co}}_{2}\mathrm{MnSi}(001)$ thin film buried under a MgO(2 nm) layer at both temperatures of 21 and 300 K. As expected from the half-metallicity in ${\mathrm{Co}}_{2}\mathrm{MnSi}$, we found that the majority (minority) spin spectrum shows a metallic Fermi edge (a band gap), leading the high spin polarization of \ensuremath{\sim}90% at around the Fermi level at a temperature of 21 K. The spin-resolved HAXPES experiments revealed that the half-metallicity of ${\mathrm{Co}}_{2}\mathrm{MnSi}$ in the bulk region is independent on the temperature up to 300 K. The experiments also revealed the slight changes in the majority spin spectral shapes and the shift of the valence band maximum of the minority spin states with temperature. By comparing the experimental results with the first-principles calculations at a finite temperature obtained by the disordered local moment method, it is suggested that the slight changes in the majority and minority spin HAXPES spectra of ${\mathrm{Co}}_{2}\mathrm{MnSi}$ with temperature is mainly caused by the temperature-dependent Co $3d$ electronic states. It is also suggested that the conduction band minimum of the minority spin states is located sufficiently above the Fermi level at temperature up to 300 K.

Selective electronic excitations in nearly half-metallic Heusler alloy NiFeMnSn—A Raman spectroscopic study

Half-metallic ferromagnetic full Heusler alloy NiFeMnSn is a promising material in spintronic device fabrication as it carries high spin polarization and high Curie temperature (Tc = 405 K). Understanding electronic excitations in a spin-polarized band structure is essential for the further use of this material in spin-based devices and to optimize the spin-dependent electronic structure in related compounds. In this Letter, we report electronic Raman scattering of NiFeMnSn with spectral signatures at a higher wavenumber than expected from the calculated phonon modes of the system. Temperature-dependent Raman spectroscopy demonstrates a non-monotonic behavior of the Raman shift with temperature across Tc. The orbital resolved electronic density of states and electronic band structure for both spin channels of the system, as obtained from the first principles density functional theory calculations, suggest that the observed Raman signatures originate from the Fe d orbital and its splitting due to the crystal field near the Fermi level. Furthermore, a strong magnetic field dependence of the spectral profile is observed. The study not only exhibits electronic Raman scattering in a Heusler alloy compound, which was unexplored to date, but also establishes Raman scattering as a promising probe to study the orbital-resolved partial density of states in the band structure near the Fermi level of a Heusler alloy.

Investigating the strain controlled epitaxial growth of Mn3Ge films through thickness modulation

Mn3Ge, a typical member of the Heusler family, has a high spin polarization and large spin Hall angle, making it a potential material for spintronic devices. Regarded as a topological Weyl semi-metal, Mn3Ge could be applied in topological spintronics owing to its special Fermi-arc-type surface states and various spin transport properties. In this study, we grew high-quality perpendicularly magnetized Mn3Gefilms through magnetron sputtering. X-ray diffraction (XRD) showed that hexagonal antiferromagnetic Mn3Ge was mixed with tetragonal ferromagnetic Mn3Ge. Thickness-dependent double-phase Mn3Ge films with large magnetic anisotropy and robust anomalous Hall effect (AHE) were obtained. The triangular spin structure of hexagonal Mn3Ge enhances the AHE; however, it shrinks the coercivity of the tetragonal ferromagnetic property. This manipulation of coexisting multi-phases comes from the strain of the substrate during growth, achieved by controlling the film thickness. Structural, magnetic, and transport measurements demonstrated stress modulation of the defect pinning, magnetic anisotropy, and spin transport properties. The coexistence of antiferromagnetic and ferromagnetic Mn3Ge provides the possibility of a new generation of Mn3X-based devices for applications in spin-torque memories.

Chiral-Molecule-Based Spintronic Devices.

Spintronics and molecular chemistry have achieved remarkable achievements separately. Their combination can apply the superiority of molecular diversity to intervene or manipulate the spin-related properties. It inevitably brings in a new type of functional devices with a molecular interface, which has become an emerging field in information storage and processing. Normally, spin polarization has to be realized by magnetic materials as manipulated by magnetic fields. Recently, chiral-induced spin selectivity (CISS) wasdiscovered surprisingly that non-magnetic chiral molecules can generate spin polarization through their structural chirality. Here, the recent progress of integrating the strengths of molecular chemistry and spintronics is reviewed by introducing the experimental results, theoretical models, and device performances of the CISS effect. Compared to normal ferromagnetic metals, CISS originating from a chiral structure has great advantages of high spin polarization, excellent interface, simple preparation process, and low cost. It has the potential to obtain high efficiency of spin injection into metals and semiconductors, getting rid of magnetic fields and ferromagnetic electrodes. The physical mechanisms, unique advantages, and device performances of CISS are sequentially clarified, revealing important issues to current scientific research and industrial applications. This mini-review points out a key technology of information storage for future spintronic devices without magnetic components.

First-principles calculations to investigate new ferromagnetic quaternary Heusler alloys FeZrTiZ(Z=Si, Sn, Pb): Compatible for spin polarized device and waste heat recovery applications

In this article, we have studied the structural, electronic, magnetic, mechanical and thermoelectric properties of new quaternary Heusler alloys FeZrTiZ (Z = Si, Sn, Pb), using ab-initio simulation methods. Our structural phase stability studies show that all these compounds stabilize in Y1-type structure and showing ferromagnetic ground state. From the calculation based on Generalized Gradient Approximation method we found that all these alloys are having half metallic behavior with the band gap value of around 1eV in one of the spin channels. The half metallic nature of these alloys is a precursor for high spin polarization. These alloys also satisfy the Slater-Pauling rule with magnetic moment of MT = NV − 18 for half metallicity and as a result they have a total magnetic moment of 2μB. The calculated elastic constants convey the mechanical stability of these alloys and though they have a cubic structure they exhibit strong mechanical anisotropy with ductile behavior. The Seebeck coefficient and the thermoelectric figure of merit were calculated using semi-classical Boltzmann transport theory. The highest Seebeck coefficient value for FeZrTiZ (Z = Si, Sn, Pb) is 110.5 μV/K, 121.8 μV/K and 100.6 μV/K respectively at the temperature 900 K, 600 K and 750 K and the corresponding figure of merit is 0.85, 0.9 and 0.59. The observation of half metallicity indicates that these materials can be used in spintronic devices and the observation of substantial thermoelectric figure of merit suggests that these materials can be used in waste heat recovery.

The effect of spin polarization on double electron-electron resonance (DEER) spectroscopy.

Double electron-electron resonance (DEER) spectroscopy measures the distribution of distances between two electron spins in the nanometer range, often on doubly spin-labeled proteins, via the modulation of a refocused spin echo by the dipolar interaction between the spins. DEER is commonly conducted under conditions where the polarization of the spins is small. Here, we examine the DEER signal under conditions of high spin polarization, thermally obtainable at low temperatures and high magnetic fields, and show that the signal acquires a polarization-dependent out-of-phase component both for the intramolecular and intermolecular contributions. For the latter, this corresponds to a phase shift of the spin echo that is linear in the pump pulse position. We derive a compact analytical form of this phase shift and show experimental measurements using monoradical and biradical nitroxides at several fields and temperatures. The effect highlights a novel aspect of the fundamental spin physics underlying DEER spectroscopy.

Anomalous Hall effect and perpendicular magnetic anisotropy in ultrathin ferrimagnetic NiCo2O4 films

The inverse spinel ferrimagnetic NiCo2O4 possesses high magnetic Curie temperature TC, high spin polarization, and strain-tunable magnetic anisotropy. Understanding the thickness scaling limit of these intriguing magnetic properties in NiCo2O4 thin films is critical for their implementation in nanoscale spintronic applications. In this work, we report the unconventional magnetotransport properties of epitaxial (001) NiCo2O4 films on MgAl2O4 substrates in the ultrathin limit. Anomalous Hall effect measurements reveal strong perpendicular magnetic anisotropy for films down to 1.5 unit cell (1.2 nm), while TC for 3 unit cell and thicker films remains above 300 K. The sign change in the anomalous Hall conductivity (σxy) and its scaling relation with the longitudinal conductivity (σxx) can be attributed to the competing effects between impurity scattering and band intrinsic Berry curvature, with the latter vanishing upon the thickness driven metal–insulator transition. Our study reveals the critical role of film thickness in tuning the relative strength of charge correlation, Berry phase effect, spin–orbit interaction, and impurity scattering, providing important material information for designing scalable epitaxial magnetic tunnel junctions and sensing devices using NiCo2O4.

Effect of off-stoichiometric composition on half-metallic character of Co2Fe(Ga,Ge) investigated using saturation magnetization and giant magnetoresistance effect

We investigated the Ge-composition (γ) dependence of the saturation magnetization of Co2Fe(Ga, Ge) (CFGG) thin films and the magnetoresistance (MR) ratio of CFGG-based current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) devices together with first-principles calculations of the electronic states of CFGG. Theoretical calculations showed that spin polarization is highest at the stoichiometric composition γ = 0.56 in Co2Fe1.03Ga0.41Ge γ and that it decreases in off-stoichiometric CFGG, mainly due to the formation of CoFe antisites for Ge-deficient compositions and FeCo antisites for Ge-rich compositions, where CoFe (FeCo) indicates that Co (Fe) atoms replace the Fe (Co) sites. The saturation magnetic moment (μ s) per formula unit decreased monotonically as γ increased from 0.24 to 1.54 in Co2Fe1.03Ga0.41Ge γ . The μ s was closest to the Slater–Pauling value predicted for half-metallic CFGG at the stoichiometric composition γ = 0.56, indicating that stoichiometric CFGG has a half-metallic nature. This is consistent with the result for the theoretical spin polarization. In contrast, the MR ratio of CFGG-based CPP-GMR devices increased monotonically as γ increased from 0.24 to 1.10 and reached an MR ratio of 87.9% at the Ge-rich composition γ = 1.10. Then, the MR ratio decreased rapidly as γ increased from 1.10 to 1.48. Possible origins for the slight difference between the Ge composition at which the highest MR ratio was obtained (γ = 1.10) and that at which the highest spin polarization was obtained (γ = 0.56) are improved atomic arrangements in a Ge-rich CFGG film and the reduction of effective Ge composition due to Ge diffusion in the GMR stacks.

Atomic and Molecular Layer Deposition of Chiral Thin Films Showing up to 99% Spin Selective Transport.

Spin electronics is delivering a much desired combination of properties such as high speed, low power, and high device densities for the next generation of memory devices. Utilizing chiral-induced spin selectivity (CISS) effect is a promising path toward efficient and simple spintronic devices. To be compatible with state-of-the-art integrated circuits manufacturing methodologies, vapor phase methodologies for deposition of spin filtering layers are needed. Here, we present vapor phase deposition of hybrid organic-inorganic thin films with embedded chirality. The deposition scheme relies on a combination of atomic and molecular layer deposition (A/MLD) utilizing enantiomeric pure alaninol molecular precursors combined with trimethyl aluminum (TMA) and water. The A/MLD deposition method deliver highly conformal thin films allowing the fabrication of several types of nanometric scale spintronic devices. The devices showed high spin polarization (close to 100%) for 5 nm thick spin filter layer deposited by A/MLD. The procedure is compatible with common device processing methodologies.

1366-P: Examining Central Carbon Metabolic Flux in the Perfused Exocrine Pancreas Using Dissolution Dynamic Nuclear Polarization

The pancreas functions as both an endocrine and exocrine gland. The endocrine component consists of the islets of Langerhans, whereas the exocrine tissue produces digestive enzymes through the ductal system. Although the majority of Type I Diabetes research has focused on the islets, the exocrine tissue is likely implicated in T1D as well. This research utilizes a novel method to investigate exocrine pancreas metabolism with a pancreas perfusion system. I hypothesized that dissolution dynamic nuclear polarization (dDNP) combined with the pancreas perfusion system would provide real-time measurements of central carbon metabolic turnover in the exocrine pancreas. DNP is a phenomenon in which a transfer of high spin polarization greatly enhances the signal in the resulting nuclear magnetic resonance (NMR) spectra. This research compares dDNP measurements in the exocrine pancreas in C57BL/6 male mice under varying glucose conditions. It also examines central carbon metabolism using this system in the T1D mouse model NOD.Rag1-/-.AI4α/β and the NOD.Rag1-/- control. After cannulation of the common bile duct, the exocrine pancreas was perfused for 30 minutes with perfusate containing either 3mM or 16.7mM glucose. Tissue viability was confirmed throughout the perfusion with oxygen consumption measurements. dDNP was performed using the trityl radical and 4mM [1-13C]pyruvate. NMR spectra were collected on a 600MHz instrument with a 10mm [13C]-optimized cryoprobe and analyzed with Bruker TopSpin. Several metabolites were identified and quantified in all measured spectra, demonstrating the detection of real-time metabolic turnover. Ultimately, this work demonstrates that dissolution dynamic nuclear polarization can be used to evaluate metabolic flux in the pancreas in multiple mouse models. Future will investigate the real-time metabolic response of the exocrine pancreas to insulin concentrations in the T1D disease model. Disclosure A.Rushin: None. M.Mcleod: None. M.Ragavan: None. M.Merritt: None. Funding National Institutes of Health (T32 DK10876) National Science Foundation (DMR-1644779)

2D spin transport through graphene-MnBi2Te4 heterojunction

The development of two-dimensional (2D) magnetic semiconductors promotes the study of nonvolatile control of magnetoelectric nanodevices. MnBi2Te4 is the first realization of antiferromagnetic topological insulator. In semiconductor circuits, metal-semiconductor contacts are usually essential. In future all-carbon circuits, graphene is a promising material for 2D conductive connections. This work studies electronic transport through graphene-MnBi2Te4-graphene junctions. We find that graphene-MnBi2Te4 interfaces are perfect Ohmic contacts, which benefits the use of MnBi2Te4 in carbon circuits. The currents through MnBi2Te4 junctions possess high spin polarization. Compared with usual van der Waals junctions, lateral graphene-MnBi2Te4-graphene junctions present a lower barrier and much higher conductance to electrons. These findings may provide guidance for further study of 2D spin filtering.

Study on FeCr thin film for a spintronic material with negative spin polarization

Negative spin polarization materials generate a spin current whose spin direction is opposite to the magnetization direction. This characteristic is technologically important because it increases the freedom in the design of spintronic devices. In this paper, we studied FeCr from the viewpoints of band structure, atomic magnetic moments, and local atomic arrangement to explore its potentiality as a negative spin polarization material. First-principles calculations on the disordered FeCr alloy predicted a high negative spin polarization, which was attributed to the band matching of the minority spin. We experimentally fabricated Fe1-xCrx thin films in the Cr concentration (x) range from 0.2 to 0.4 by sputter deposition and demonstrated inverse magnetoresistance using current-perpendicular-to-plane giant magnetoresistance (GMR) devices, which provided evidence of negative spin polarization. The spin polarization of Fe0.7Cr0.3 estimated from the GMR device measurements was −0.28 and fell below the calculated value. Synchrotron X-ray magnetic circular dichroism measurements showed a ferrimagnetic configuration of the Fe and Cr magnetic moments. The Fe moment showed a large moment over a wide Cr concentration range, whereas the Cr moment decreased with the Cr concentration, which agreed with the calculation result. Synchrotron Mössbauer spectroscopy measurements indicated the inhomogeneity of the FeCr composition even in the as-deposited state. Fe-rich regions were formed after annealing, reflecting the phase separation nature of the Fe-Cr system. Inhomogeneity was not considered in the calculation and could be the origin of the smaller negative spin polarization observed in the experiment.