Two-dimensional multiferroic RuClF/AgBiP2S6 van der Waals heterostructures with valley splitting properties and controllable magnetic anisotropy.

The investigation of new properties in two-dimensional (2D) multiferroic heterostructures is significant. In this work, the electronic properties and magnetic anisotropy energies (MAEs) of 2D multiferroic RuClF/AgBiP2S6 van der Waals (vdW) heterostructures are systematically studied by first principles calculations based on density functional theory (DFT). The Hubbard on-site Coulomb parameter (U) of Ru atoms is necessary to account for the strong correlation among the three-dimensional electrons of Ru. RuClF/AgBiP2S6 heterostructures in different polarizations (RuClF/AgBiP2S6-P↑ and RuClF/AgBiP2S6-P↓) are ferromagnetic semiconductors with stable structures. Valley polarizations are present in the band structures of RuClF/AgBiP2S6 heterostructures with spin-orbit coupling (SOC), the valley splitting energies of which are 279 meV and 263 meV, respectively. The MAEs of RuClF/AgBiP2S6 heterostructures indicate perpendicular magnetic anisotropy (PMA), which are primarily attributed to the differences in matrix elements within Ru (dyz, dz2) orbitals. In addition, valley splittings and MAEs of RuClF/AgBiP2S6 heterostructures are modified at different biaxial strains. Specifically, the highest valley splittings are 283 meV and 287 meV at ε = 2%, while they disappear at ε = -6%. The PMA of RuClF/AgBiP2S6-P↑ is gradually decreased at biaxial strains of -6% to 2%, and MAE is transformed into in-plane magnetic anisotropy (IMA) at ε = 4%. RuClF/AgBiP2S6-P↓ maintains PMA at different strains. The study of non-volatile electrical control of valley splitting phenomena in multiferroic RuClF/AgBiP2S6 heterostructures is crucial in the field of valleytronic devices, which has important theoretical significance.

Valley polarization and magnetic anisotropy of two-dimensional Ni2Cl3I3/MoSe2 heterostructures.

Two-dimensional (2D) Janus trihalides have attracted widespread attention due to their potential applications in spintronics. In this work, the valley polarization of MoSe2 at the K' and K points can be modulated by Ni2Cl3I3, a new 2D Janus trihalide. The Ni2Cl3I3/MoSe2 heterostructure has an in-plane magnetic anisotropy energy (IMA) and is characterized by three distinct electronic structures: metallic, semiconducting, and half-metallic. It is noted that the semiconducting state features a band gap of 0.07 eV. When spin-orbit coupling (SOC) is considered, valley polarization is exhibited in the Ni2Cl3I3/MoSe2 heterostructure, with the degree of valley polarization varying across different configurations and reaching a maximum value of 4.6 meV. The electronic properties, valley polarization and MAE of the system can be tuned by biaxial strains. The application of a biaxial strain ranging from -6% to +6% can enhance the valley polarization value from 0.9 meV to 12.9 meV. The directions of MAE of the Ni2Cl3I3/MoSe2 heterostructure can be changed at biaxial strains of -6%, +2%, +4% and +6%. The above calculation results show that the heterostructure system possesses rich electronic properties and tunability, with extensive potential applications in the fields of spintronic and valleytronic devices.

A first-principles study on Ni-decorated MoS2 for efficient formaldehyde degradation over a wide temperature range.

The development of a high-efficiency, low-cost, and environmentally friendly catalyst for formaldehyde degradation is crucial for addressing the issue of indoor formaldehyde pollution. Given that modern individuals spend over 90% of their time indoors, effectively tackling indoor formaldehyde pollution holds significant importance. Therefore, this paper proposes an efficient catalyst for formaldehyde degradation: surface modification of MoS2 by single-atom Ni, which can convert formaldehyde into harmless H2O and CO2. The DFT method is employed to systematically investigate the oxidative degradation pathways of formaldehyde on the surface of Ni-doped MoS2. The research focuses on two common oxidative degradation pathways in both the L-H mechanism and E-R mechanism. Our findings demonstrate that these four reaction paths occur spontaneously within the temperature range of 300-800 K with a reaction equilibrium constant greater than 105. Moreover, even under extreme temperature conditions (100 K), the reaction rate remains favorable. Furthermore, our findings indicate that the minimum activation energy is merely 0.91 eV and H2O and CO2 only need to overcome an energy barrier of 0.71 eV for desorption from the catalyst surface. This substantiates its potential application both in indoor environments and under extreme temperature conditions. This theoretical research provides innovative ideas and strategies for effectively oxidizing formaldehyde.

Band inversion and switchable magnetic properties of two-dimensional RuClF/WSe2 van der Waals heterostructures.

Two-dimensional (2D) van der Waals (vdW) heterostructures have potential applications in new low-dimensional spintronic devices owing to their unique electronic properties and magnetic anisotropy energies (MAEs). The electronic structures and magnetic properties of RuClF/WSe2 heterostructure are calculated using first-principles calculations. The most stable RuClF/WSe2 heterostructure is selected for property analysis. RuClF/WSe2 heterostructure has half-metallicity. Considering spin-orbit coupling (SOC), band inversion is present in the RuClF/WSe2 heterostructure, which is also demonstrated by the weight of the energy contributions. The local density of states (LDOS) of the edge states can provide strong evidence that the RuClF/WSe2 heterostructure has topological properties. The MAE of RuClF/WSe2 heterostructure is in-plane magnetic anisotropy (IMA), which mainly originates from the contribution of matrix element difference in Ru (dxy, dx2-y2) orbitals. The electronic properties and MAE of RuClF/WSe2 heterostructure can be regulated by biaxial strains and electric fields. The band inversion phenomenon is enhanced at electric fields in the opposite direction, which is also modified at different biaxial strains. However, the band inversion phenomenon disappears at the biaxial strains of 6% and an electric field of 0.5 V Å-1. The MAE of RuClF/WSe2 heterostructure is transformed from IMA into perpendicular magnetic anisotropy (PMA) at certain compressive strains and positively directed electric fields. The above results indicate that the RuClF/WSe2 heterostructure has potential applications in spintronic devices.

Dirac semimetallic Janus Ni-trihalide monolayer with strain-tunable magnetic anisotropy and electronic properties.

Two-dimensional (2D) ferromagnetic (FM) semiconductors have been paid much attention due to the potential applications in spintronics. Here, the electronic and magnetic properties of 2D Janus Ni-trihalide monolayer Ni2X3Y3 (X, Y = I, Br, Cl; X ≠ Y) are investigated by first-principle calculations. The properties of Ni2X3Y3 (X, Y = I, Br, Cl; X ≠ Y) monolayers are compared by selecting the NiCl3 monolayer as the reference material. Ni2X3Y3 monolayers have two distinct magnetic ground states of ferromagnetic (FM) and antiferromagnetic (AFM). In the Ni2X3Y3 monolayer, two different orbital splits were observed, one semiconductor state and the other semimetal state. The semimetal state of Ni2X3Y3 can be tuned to semiconductor or metallic state when biaxial strain is applied. The magnetic anisotropy energy (MAE) of the Ni2X3Y3 monolayer can display variations compared to that of the NiCl3 monolayer, with the direction of easy magnetization being influenced by the specific halogen elements present. The easy magnetization direction of Ni2X3Y3 can also be changed by applying biaxial strain. The Tc of Ni2X3Y3 is predicted to be about 100 K according to the calculation of the EAFM-EFM model. The design of the Janus Ni2X3Y3 structure has expanded the range of 2D magnetic materials, a significant contribution has been made to the advancement of spintronics and its applications.

Two dimensional Janus RuXY (X, Y = Br, Cl, F, I, X ≠ Y) monolayers: ferromagnetic semiconductors with spontaneous valley polarization and tunable magnetic anisotropy.

Two-dimensional (2D) ferromagnetic (FM) materials with valley polarization are highly desirable for use in valleytronic devices. The 2D Janus materials have fascinating physical properties due to their asymmetrical structures. In this work, the electronic structure and magnetic properties of Janus RuXY (X, Y = Br, Cl, F, I, X ≠ Y) monolayers are systematically studied using first-principles calculations. RuBrCl, RuBrF, and RuClF monolayers are all FM semiconductors. The valley polarization is present in the band structure and this is determined by the spin orbit coupling (SOC). The valley splitting energy of the RuClF monolayer is as large as 204 meV, with a perpendicular magnetic anisotropy (PMA) energy of 1.918 mJ m-2 and a Curie temperature of 316 K. Therefore, spontaneous valley polarization at room temperature will be seen in the RuClF monolayer. The Curie temperature of the RuBrF monolayer is higher than that of the RuClF, but the magnetic anisotropy energy (MAE) is in-plane magnetic anisotropy (IMA). The valley splitting energy of the RuBrCl monolayer is higher and the PMA energy is lower than that of the RuClF monolayer. The Curie temperature was only 197 K. The valley polarization was modulated in the RuXY monolayers at different biaxial strains, during which the semiconductor properties are still maintained. The PMA of the RuClF and RuBrCl monolayers is enhanced by the biaxial compressive strains, which are mainly attributed to the variation of the (dyz, d2z) orbital matrix elements of the Ru atoms. The MAE of the RuBrF monolayer is tuned from IMA into PMA at a biaxial strain of -6%. These results show an example of a 2D Janus ferrovalley material.

Spin-splitting and switchable half-metallicity in a van der Waals multiferroic CuBiP2Se6/GdClBr heterojunction.

Multiferroic van der Waals (vdW) heterojunctions have a strong and nonvolatile magnetoelectric coupling effect, which is of great significance in spintronic devices. The electronic structure and magnetic properties of a GdClBr/CuBiP2Se6 vdW multiferroic heterojunction have been calculated using first-principles methods. Due to the spin-up charge transfer and Zeeman field, the ferroelectric CuBiP2Se6 exhibits spin splitting at the gamma point. It is found that the electronic structure and magnetic properties of the GdClBr/CuBiP2Se6 vdW multiferroic heterojunction have been significantly modulated by the electric polarization of CuBiP2Se6. During the reversal of the ferroelectric polarization of CuBiP2Se6, the ferromagnetic GdClBr monolayer transforms from a semiconductor to a half-metal. Meanwhile, in both upward and downward ferroelectric polarization, the GdClBr/CuBiP2Se6 heterojunction exhibits perpendicular magnetic anisotropy with a Curie temperature of 239 K. As the strain changes from -6% to 6%, the band structure of GdClBr shifts upward, and the band structure of CuBiP2Se6 shifts downward. Compressive strain can increase the Curie temperature of the GdClBr/CuBiP2Se6 heterojunction. The magnetic anisotropy of heterojunctions highly depends on biaxial strain, where the perpendicular (in-plane) magnetic anisotropy increases with the increased compressive (tensile) strain. The vdW multiferroic GdClBr/CuBiP2Se6 heterojunction has potential applications in spintronic devices.

Two dimensional Zr2CO2/H-FeCl2van der Waals heterostructures with tunable band gap, potential difference and magnetic anisotropy.

Two dimensional (2D) van der Waals (vdW) heterostructures have potential applications in novel low dimensional spintronic devices due to their unique electronic and magnetic properties. Here, the electronic and magnetic properties of 2D Zr2CO2/H-FeCl2heterostructures are calculated by first principles calculations. The 2D Zr2CO2/H-FeCl2heterostructures are magnetic semiconductor. The electronic structure and magnetic anisotropy of Zr2CO2/H-FeCl2heterostructure can be regulated by the biaxial strain and external electric field. The band gap and potential difference of Zr2CO2/H-FeCl2heterostructure can be affected by in-plane biaxial strain. At a compressive strain of -8%, the Zr2CO2/H-FeCl2heterostructure becomes metallic. All of the Zr2CO2/H-FeCl2heterostructures are magnetic with in-plane magnetic anisotropy (IMA). The Zr2CO2/H-FeCl2heterostructure is a semiconductor at the electric field from -0.5 V Å-1to +0.5 V Å-1. Furthermore, Zr2CO2/H-FeCl2heterostructure shows IMA at the negative electric field, while it shows perpendicular magnetic anisotropy at the positive electric field. These results show that Zr2CO2/H-FeCl2heterostructure has potential applications in multifunctionalnanoelectronic devices.

Valley splitting and magnetic anisotropy in two-dimensional VI3/MSe2 (M = W, Mo) heterostructures.

As a new van der Waals ferromagnetic material, VI3 can be used to lift the valley degeneracy of transition metal dichalcogenides at the K' and K points. Here, the electronic structure and magnetic anisotropy of the VI3/MSe2 (M = W, Mo) heterostructures are studied. The VI3/WSe2 heterostructure is semiconducting with a band gap of 0.26 eV, while the VI3/MoSe2 heterostructure is metallic. Considering the spin-orbit-coupling, a maximum valley splitting of 3.1 meV appears in the VI3/WSe2 heterostructure. The biaxial strain can tune the valley splitting and magnetic anisotropy of VI3/MSe2 heterostructures. In the VI3/WSe2 heterostructure, which has the most stable stacking, valley splitting can be increased from 1.8 meV at 4% compressive strain to 3.1 meV at 4% tensile strain. At a biaxial strain of -2% to 4%, the VI3/WSe2 heterostructure maintains a small perpendicular magnetic anisotropy, while the VI3/MoSe2 heterostructure shows in-plane magnetic anisotropy under different strains. The significantly tunable electronic structure and magnetic anisotropy under biaxial strain suggest that the VI3/MSe2 heterostructures have potential applications in spintronic devices.

Induced half-metallic characteristics and enhanced magnetic anisotropy in the two-dimensional Janus V2I3Br3 monolayer by graphyne adsorption.

The recent emergence of two-dimensional (2D) Janus materials has opened a new avenue for spintronic and optoelectronic applications. However, 2D magnetic Janus materials and Janus monolayer-based magnetic heterostructures are yet to be fully studied. Herein, the stability and electronic structure of 2D Janus V2I3Br3 and V2I3Cl3 monolayers, and the electronic and magnetic properties of 2D graphyne/Janus V2I3Br3 (γ-GY/V2I3Br3) heterostructures are calculated based on the density functional theory. Janus V2I3Br3 and V2I3Cl3 monolayers are ferromagnetic semiconductors with good stability and direct band gap. By combing the graphyne layer, the Janus V2I3Br3 monolayer shows half-metallic characteristics. The electrical conductivity of the Janus V2I3Br3 monolayer in γ-GY/V2I3Br3 heterostructures is further improved, which is very favorable for the applications of the γ-GY/V2I3Br3 heterostructure in battery anodes. Moreover, the Janus V2I3Br3 monolayer possesses a smaller perpendicular magnetic anisotropy (PMA), and the PMA can be effectively enhanced by combing γ-GY. Herein, the enhanced PMA was discovered to depend on the stacking patterns of γ-GY and V2I3Br3 monolayers. Biaxial strains can further affect the PMA of the γ-GY/V2I3Br3 heterostructure. Meanwhile, at a compressive strain, the Janus V2I3Br3 monolayer in the γ-GY/V2I3Br3 heterostructure realizes the transition from the magnetic half-metallic to the magnetic metal state. These results can enrich the applications and designs of γ-GY/V2I3Br3 magnetic heterostructures in spintronic devices and energy fields.

Biaxial strain, electric field and interlayer distance-tailored electronic structure and magnetic properties of two-dimensional g-C3N4/Li-adsorbed Cr2Ge2Te6 van der Waals heterostructures.

Recently, it has been proven that the biaxial strain (ε), electric field (E) and interlayer distance (d) can effectively modulate the electronic structure and magnetic properties of two-dimensional (2D) van der Waals (vdW) heterostructures, which have potential applications in spintronic devices. Here, the electronic structure and magnetic properties of 2D g-C3N4/Li-adsorbed Cr2Ge2Te6 vdW heterostructures are investigated using first-principles calculations. Their lattice structures are seriously affected by adsorption combination. With external stimulation, the band gap of the heterostructures changes. The heterostructures are metallic at ε = -6% and -4%, and others are n-type semiconductors, where the band gap is 23 meV at ε = 6%. In addition, the magnetic moments of g-C3N4 in the adsorption systems are in the range from 0.029 to 0.226 µB. The vdW heterostructures show in-plane magnetic anisotropy (IMA) at ε = -6%, -2% and 6% and perpendicular magnetic anisotropy (PMA) at ε = -4%, 0, 2% and 4%. On applying an electric field and changing the interlayer distance, the vdW heterostructures show PMA. These results are significant to the low-dimensional spintronic devices.

Electronic structure, magnetic anisotropy and Dzyaloshinskii-Moriya interaction in Janus Cr2I3X3 (X = Br, Cl) bilayers.

Two-dimensional (2D) layers with a tunable electronic structure and magnetic properties have attracted much attention due to their unique characteristics and practical applications. Here, the electronic structure and magnetic properties of the 2D van der Waals Cr2I3X3 (X = Br, Cl) bilayers are investigated systematically by first-principles calculations. The Cr2I3X3 bilayers show the stacking-dependent magnetic ground state, where the band gap can be effectively tailored by the stacking and combination modes. In the Cr2I3Br3 (Cr2I3Cl3) bilayers, the electrostatic potential and electric polarization can be greatly affected by combination modes, which can be attributed to the parallel or antiparallel built-in electric fields between the monolayers. The Cr2I3X3 bilayers show a perpendicular magnetic anisotropy. The magnetic anisotropy energy of the Cr2I3Cl3 bilayer is larger than that of the Cr2I3Br3 bilayer, which can be attributed to the enhanced contribution of the hybridized I px and py orbitals of the Cr2I3Cl3 bilayer. Additionally, the Dzyaloshinskii-Moriya interaction of the Cr2I3Br3 bilayer can also be modulated by the combination modes. These results can boost the development of Janus 2D materials, which are useful in the design of multifunctional spintronic devices.

Tunable valley and spin splitting in 2H-VSe2/BiFeO3(111) triferroic heterostructures.

The spin and valley degrees of freedom in monolayer transition metal dichalcogenides have potential applications in spintronics and valleytronics. However, nonvolatile control on the valley and spin degrees of freedom of two-dimensional ferromagnetic materials by multiferroic materials has been rarely reported. Here, the electronic structure of monolayer 2H-VSe2/BiFeO3(111) triferroic heterostructures has been investigated by first-principles calculations. It is found that the V magnetic moment, spin and valley splitting of monolayer VSe2 can be affected by the BiFeO3(111) substrate with ferroelectric polarization and G-type antiferromagnetic order. Particularly, the reversed orientation of ferroelectric polarization and magnetic order of the BiFeO3(111) substrate can modulate the magnitude of spin and valley splitting, and change the spin splitting direction and the spin-dependent valley state in the valence band of monolayer VSe2. The coupling among ferroelectrics, magnetism and ferrovalley is realized in 2H-VSe2/BiFeO3(111) triferroic heterostructures. These results provide a new platform for multiferroic regulation in spintronics and valleytronics, which can enrich the diversity for high-performance devices based on two dimensional multiferroic heterostructures.

Magnetic proximity effect induced spin-dependent electronic structure in two-dimensional SnO by half-metallic monolayer CrN ferromagnet.

Monolayer SnO has been attracting much attention owing to its unique electronic structure, which has potential applications in nanoelectronic and optoelectronic devices. However, it is necessary to induce the spin-dependent electronic structure of monolayer SnO for its applications in spintronics. Here, in order to induce the spin polarization of monolayer SnO by magnetic proximity effects, the spin-dependent electronic structure of two-dimensional (2D) van der Waals (vdW) SnO/CrN heterostructures is calculated using first-principles calculations by considering different strains and interlayer distances. When the interlayer distance of the heterostructure increases, the Sn magnetic moment decreases, but the Cr magnetic moment increases. As the interlayer distance decreases, the band gap of SnO decreases in the spin-down channel because of the enhancements in orbital overlap and hybridization. Meanwhile, the electronic structure of monolayer SnO/CrN heterostructures can also be tailored by in-plane biaxial strain. With an increase in tensile strain, the Fermi level of monolayer SnO moves down and p-type doping appears. For compressive strains, the Fermi level of monolayer SnO moves upward and n-type doping appears. When the in-plane biaxial strain turns from compressive to tensile, the magnetic anisotropy of CrN in monolayer SnO/CrN heterostructure increases, where the easy axis is perpendicular to the CrN layer.

Ferromagnetic, Ferroelectric, and Optical Modulated Multiple Resistance States in Multiferroic Tunnel Junctions.

In data storage devices, spin, ferroelectric, or optical indices have been utilized as information carriers, and the binate couplings among the three parameters are explored to increase the resistance states and resultant data-density. However, studies holding all of the three information indices are still blank, where the increasing number of information carriers from previous two to three provides opportunities for inducing novel phenomena and distinct resistance states. In this work, using the spin-electron-photon resolved theory, we demonstrate the feasibility of spin, ferroelectric, and optical interactions, which are further detected by a spin- and ferroelectric-modulated photovoltaic effect in La2/3Sr1/3MnO3/BiFeO3/Fe4N multiferroic tunnel junctions (MFTJs). Moreover, based on the spin- and ferroelectric-induced four resistance states in MFTJs, the special photovoltaic effect shall split each resistance state into light-on and light-off switching states, which finally lead to multiple resistance states. Besides, nearly 100% spin-polarized photocurrent and large tunneling magnetoresistance (electroresistance) are realized in these MFTJs. These results reveal that interacted spin, ferroelectric, and optical indices can simultaneously serve as information carriers in storage devices, which provide guidance for developing efficient data memories.

Spin-orbit coupling induced spin polarized valley states in SrRuO3/BiIrO3 heterostructures.

The electronic properties of SrRuO3/BiIrO3 superlattices are investigated by first-principles calculations with spin-orbit coupling. The results show that the strength of hybridization near the Fermi level is dependent on the distance between the closest transition metal Ru and Ir atoms. We find that both spin and valley polarizations in bilayered BiIrO3 are achieved in Bi-terminated models. Furthermore, different stacking patterns can modulate the magnitude and sign of valley polarization and switch the p- or n-type doping of bilayered BiIrO3. Meanwhile, a spin-down polarized valley polarization of 79.5 meV can be induced in bilayered SrRuO3. The different thicknesses calculated demonstrate that the valley in the SrRuO3/BiIrO3 model is limited to the bilayered structure. The tunable valley and spin polarizations in SrRuO3/BiIrO3 superlattices would enrich the diversity and boost the development of high-performance spintronic and valleytronic devices.

Spin polarization and spin channel reversal in graphitic carbon nitrides on top of an α-Fe2O3(0001) surface.

Inducing the spin-dependent characteristics in two-dimensional (2D) materials by magnetic proximity effects is a recent targeted route for 2D spintronic devices. Here, we report the spin-dependent electronic properties of graphitic carbon nitrides (g-C2N, g-C3N and g-C4N3) on top of α-Fe2O3(0001) by first-principles calculations. The different terminations of α-Fe2O3(0001) can switch the conductivity of g-C2N from the n- to the p-type. In particular, the O- and single Fe-terminated interfaces show a half-metallic feature in g-C2N, which originates from the charge redistribution driven by work function difference and interfacial interaction. Additionally, the O-terminated interface shows stable physical adsorption, which leads to spin polarization in g-C3N and spin channel reversal in g-C4N3. These results strongly reveal that this novel system is a candidate for future graphitic carbon nitride-based spintronic devices.

Efficient band structure modulations in two-dimensional MnPSe3/CrSiTe3 van der Waals heterostructures.

As a research upsurge, van der Waals (vdW) heterostructures give rise to numerous combined merits and novel applications in nanoelectronics fields. Here, we systematically investigate the electronic structure of MnPSe3/CrSiTe3 vdW heterostructures with various stacking patterns. Then, particular attention of this work is paid on the band structure modulations in MnPSe3/CrSiTe3 vdW heterostructures via biaxial strain or electric field. Under a tensile strain, the relative band edge positions of heterostructures transform from type-I (nested) to type-II (staggered). The relocation of conduction band minimum also brings about a transition from indirect to direct band gap. Under a compressive strain, the electronic properties change from semiconducting to metallic. The physical mechanism of strain-dependent band structure may be ascribed to the shifts of the energy bands impelled by different superposition of atomic orbitals. Meanwhile, our calculations manifest that band gap values of MnPSe3/CrSiTe3 heterostructures are insensitive to the electric field. Even so, by applying a suitable intensity of negative electric field, the band alignment transition from type-I to type-II can also be realized. The efficient band structure modulations via external factors endow MnPSe3/CrSiTe3 heterostructures with great potential in novel applications, such as strain sensors, photocatalysis, spintronic and photoelectronic devices.

Tunable Valley and Spin Polarizations in BiXO3/BiIrO3 (X = Fe, Mn) Ferroelectric Superlattices.

The generation and modulation on valley and spin degrees of freedom are essential for multifunctional electronic devices. Herewith, the electronic structures in BiXO3/BiIrO3 (X = Fe, Mn) ferroelectric superlattices are studied by first-principles calculations with spin-orbital coupling. Different from the previous BiAlO3/BiIrO3 system, both valley and spin polarizations in bilayered BiIrO3 are achieved in BiXO3/BiIrO3 superlattices, where the spin polarization in the valley can be engineered by the spin orientation of Fe or Mn owing to the xy-plane orbitals. Especially, the relatively parallel and antiparallel directions of ferroelectric polarization in BiFeO3 and BiIrO3 can switch the valley injection in BiFeO3/BiIrO3 superlattices. Overall, the tunable valley and spin polarizations in BiFeO3/BiIrO3 ferroelectric superlattices pave a way for developing nonvolatile data memories and valley-spin devices.

Spin polarization and magnetic characteristics at C6H6/Co2MnSi(001) spinterface.

Organic materials with mechanical flexibility, low cost, chemical engineering, and long spin lifetime attract considerable attention for building spintronic devices. Here, a C6H6/Co2MnSi(001) spinterface is investigated by first-principles calculations and spin-polarized scanning tunneling microscopy simulations. Several high symmetry adsorption sites are discussed, together with two possible surface terminations of Co2MnSi(001). An inversion of the spin polarization is induced near EF even in the case of an external electric field, indicating that C6H6 can act as a spin filter to exploit the spin injection efficiency in organic spintronic devices. Unlike previous studies on molecule/ferromagnet interfaces, this inversion is closely related to the electronic structure of the atoms in the subsurface layer of Co2MnSi according to the orbital symmetry analysis. Furthermore, the magnetic moment and magnetic anisotropic energy (MAE) in the outermost Co2MnSi layer are studied. Particularly, in the most stable configuration, the sign of MAE is inversed due to hybridization between C p and Co dz2 orbitals, which suggests that a greater modification on MAE can be achieved by the use of a highly chemically reactive organic molecule. These findings improve the study on the engineering of magnetic properties at molecule/ferromagnetic interfaces through a single π-conjugated organic molecule.