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Nowadays there is considerable interest in the photogalvanic effect in low-dimensional devices. In this work, we built a two-dimensional Bi2C-based photodetector and explored the spin-dependent photogalvanic effect under linearly polarized light and zero-bias conditions which can produce experimentally observable photoelectron flow. It was discovered that by introducing vacancies and substitution-doping into the Bi2C photodetector, the photogalvanic effect could be enhanced by 10–100 times that of a pristine photodetector, which is sufficient to be detected in experiments. Moreover, due to strong spin–orbit interactions, the Bi2C photodetector can produce very high spin polarization, even 100% full spin polarization, and pure spin current at a specific incident angle and photon energy, for example in the Bi1-vacancy Bi2C photodetector. In addition, the photon energy of incident light can regulate the produced spin photocurrent, which shows considerable anisotropy. Our results highlight the potential of the Bi2C photodetector as a versatile device in optoelectronics and spintronics applications. [ABSTRACT FROM AUTHOR]

The spin Hall effect (SHE) allows efficient generation of spin polarization or spin current through charge current and plays a crucial role in the development of spintronics. While SHE typically occurs in non-magnetic materials and is time-reversal even, exploring time-reversal-odd (T-odd) SHE, which couples SHE to magnetization in ferromagnetic materials, offers a new charge-spin conversion mechanism with new functionalities. Here, we report the observation of giant T-odd SHE in Fe3GeTe2/MoTe2 van der Waals heterostructure, representing a previously unidentified interfacial magnetic spin Hall effect (interfacial-MSHE). Through rigorous symmetry analysis and theoretical calculations, we attribute the interfacial-MSHE to a symmetry-breaking induced spin current dipole at the vdW interface. Furthermore, we show that this linear effect can be used for implementing multiply-accumulate operations and binary convolutional neural networks with cascaded multi-terminal devices. Our findings uncover an interfacial T-odd charge-spin conversion mechanism with promising potential for energy-efficient in-memory computing. Charge-to-spin conversion allows for the generation and control of spin polarization via a charge current. Typically, this is done with non-magnetic materials with large spin-orbit interactions such as Platinum. Herein, Dai et al demonstrate an intriguing charge-to-spin mechanism, a magnetic spin Hall effect, in a van der Waals heterostructure. [ABSTRACT FROM AUTHOR]

We have looked at a very interesting class of Heusler alloy that has received a lot of theoretical research but a very little experimental attention. Mn2TiSi Heusler alloy was synthesized by a conventional vacuum arc remelting process. The formation of Heusler phase along with the secondary phases was observed after annealing it at 773 K for 120 h. The X-ray diffraction pattern illustrates the presence of cubic B2 disordered phase along with a secondary phase with a lattice parameter of 5.82 Å. The microstructure and compositional analysis of Mn2TiSi alloy shows the presence of distribution of Mn, Ti, and Si elements according to their stoichiometric ratio. The magnetic measurements show a ferromagnetic nature with Curie temperature (TC) around 203 K. With low magnetic moment and coercivity, Mn2TiSi can be used for switching applications because of its fast magnetization reversal. So, Mn2TiSi becomes the greatest choice for use in spintronics due to its low magnetic moment and low coercivity. [ABSTRACT FROM AUTHOR]

In the present work, we investigate the electronic structure and magnetism of InN nanoribbon doped with 3d Mn atoms in different positions by first-principle density functional calculations. The structural stability is described by using the calculated total energy of the doped nanoribbons including the antiferromagnetic (AFM) and the ferromagnetic (FM) coupled states. Our calculations show that the ground state is ferromagnetic regardless of the position of Mn atoms. The dependence of bandgap and spin polarization on Mn positions makes it possible to control the electronic properties by choosing the impurity position and applying these structures in nanoelectronics and spintronics. [ABSTRACT FROM AUTHOR]

Much attention has been paid to the hidden Rashba effect exhibiting an intriguing spin-layer locking phenomenon observed in two-dimensional materials with inversion symmetry. This effect provides a new possibility for manipulating Rashba spin polarization even in centrosymmetric materials. We propose a mechanism exhibiting an unconventional hidden Rashba effect showing a unique helical spin texture in which two Fermi circles in different bands have the same spin helicity exhibiting a complete spin separation in space. We demonstrate such an unconventional hidden Rashba effect by showing the unique electronic structures of two-dimensional InTe with inversion symmetry investigated by the first-principles calculations. It is found that spins in both the inner and outer bands with the one helicity are located in the top sublayer whereas spins with the other helicity are in the bottom sublayer indicating a complete spatial spin separation. Strong spin-orbit coupling and a band inversion among two pairs of spin-degenerate bands are the main origins for the unconventional hidden Rashba involving two pairs of spin-degenerate bands rather than one pair, which gets usually involved in the conventional (hidden) Rashba effects. This new type of the hidden Rashba effect observed in two-dimensional InTe would broaden our understanding of the underlying physics of spin polarization phenomena eventually leading to a potential application in future spintronics. [ABSTRACT FROM AUTHOR]

The injection of a pure spin current into a conducting helimagnet is investigated. The characteristic decay lengths for the spin current injected into the helimagnet are determined, and their physical meaning is described. It is shown that instead of the spin diffusion length, helimagnets are characterized by the decay length that is always smaller than the spin diffusion length, the difference in these lengths being determined by the ratio of the helimagnet spiral period to the spin diffusion length. We predict the existence of the "effect of the chiral polarization of a pure spin current," i.e., the emergence of the spin current with longitudinal (transverse) polarization, which depends on the spiral chirality, upon the injection of a pure spin current with the transverse (longitudinal) polarization relative to the spiral axis. [ABSTRACT FROM AUTHOR]

A theory of spin and charge transport in bounded metallic magnets has been constructed, which takes into account the effects of spin-orbit scattering of conduction electrons by crystal lattice defects. The theory can be used to describe the spin Hall effect and the anomalous Hall effect and can serve as a basis for describing the phenomena of spin-orbitronics. Phenomenological boundary conditions for the charge and spin fluxes at the interface between two different metals have been formulated, on the basis of which the injection of a pure spin current into a helimagnet, which arises in a normal metal as a manifestation of the spin Hall effect, is described. The existence of an "effect of chiral polarization of a pure spin current" is predicted, which consists in the appearance in a helimagnet of a longitudinally polarized pure spin current and a longitudinal component of the nonequilibrium electron magnetization, depending on the chirality of the helimagnet helix, upon injection of a transversely polarized spin current from a normal metal. [ABSTRACT FROM AUTHOR]

The structural parameters, exchange splittings, half-metallic property, electronic features and magnetic performances of Ba1−xCrxS materials were determined by utilizing the computational methods of density functional theory. The localized magnetic spins in the Ba1−xCrxS result from the effect of the hole carriers caused by the d shells of Cr atom, hybridizing with p levels of S atom. The ferromagnetism is mostly endorsed by the exchange splitting owing to its large contribution than that of the crystal field. The Ba1−xCrxS (x = 0.25), Ba1−xCrxS (x = 0.5)and Ba1−xCrxS (x = 0.75) materials have half-metallic characteristic with ferromagnetic state, where their electronic structures demonstrate spin polarizations of 100% with half-gaps of 0.815, 0.912 and 0.72 eV, respectively. Therefore, Ba1−xCrxS systems have better magneto-electronic performances, making them appropriate half-metallic materials for spin-injection applications for spintronics. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The spintronic properties of molecules are essential for the development of multifunctional organic spintronic devices. Here, the spin polarization of bis-(8-hydroxyquinoline) zinc (Znq2) molecule upon electron and hole injection has been theoretically studied by using density-functional theory calculations. It is found that both the injected excess electrons and holes are highly spin polarized in Znq2, leading to an approximately linearly increased magnetic moments with the amount of the charge injected. Our calculation also reveals that the spin polarization upon excess electron and hole injection may attribute to the exchange splitting of lowest unoccupied molecular orbital (LUMO)-related p states of N and C atoms of pyridyl rings and the highest occupied molecular orbital (HOMO)-related p states of O and C atoms of the phenoxide rings, respectively. The d0 ferromagnetism in the charge-injected Znq2 molecule is quite promising for organic spintronic devices. [ABSTRACT FROM AUTHOR]

Electric currents carrying a net spin polarization are widely used in spintronics, whereas globally spin-neutral currents are expected to play no role in spin-dependent phenomena. Here we show that, in contrast to this common expectation, spin-independent conductance in compensated antiferromagnets and normal metals can be efficiently exploited in spintronics, provided their magnetic space group symmetry supports a non-spin-degenerate Fermi surface. Due to their momentum-dependent spin polarization, such antiferromagnets can be used as active elements in antiferromagnetic tunnel junctions (AFMTJs) and produce a giant tunneling magnetoresistance (TMR) effect. Using RuO2 as a representative compensated antiferromagnet exhibiting spin-independent conductance along the [001] direction but a non-spin-degenerate Fermi surface, we design a RuO2/TiO2/RuO2 (001) AFMTJ, where a globally spin-neutral charge current is controlled by the relative orientation of the Néel vectors of the two RuO2 electrodes, resulting in the TMR effect as large as ~500%. These results are expanded to normal metals which can be used as a counter electrode in AFMTJs with a single antiferromagnetic layer or other elements in spintronic devices. Our work uncovers an unexplored potential of the materials with no global spin polarization for utilizing them in spintronics. Spin-polarised electric currents have been studied extensively for use in spintronics, while their spin-neutral counterparts have been largely ignored. Here Shao et al show that such spin-neutral currents can be controlled by the Neel vector orientation of an antiferromagnet and detected using an antiferromagnetic tunnel junction. [ABSTRACT FROM AUTHOR]

Out-of-plane spin polarization σz has attracted increasing interests of researchers recently, due to its potential in high-density and low-power spintronic devices. Noncollinear antiferromagnet (AFM), which has unique 120° triangular spin configuration, has been discovered to possess σz. However, the physical origin of σz in noncollinear AFM is still not clear, and the external magnetic field-free switching of perpendicular magnetic layer using the corresponding σz has not been reported yet. Here, we use the cluster magnetic octupole in antiperovskite AFM Mn3SnN to demonstrate the generation of σz. σz is induced by the precession of carrier spins when currents flow through the cluster magnetic octupole, which also relies on the direction of the cluster magnetic octupole in conjunction with the applied current. With the aid of σz, current induced spin-orbit torque (SOT) switching of adjacent perpendicular ferromagnet is realized without external magnetic field. Our findings present a new perspective to the generation of out-of-plane spin polarizations via noncollinear AFM spin structure, and provide a potential path to realize ultrafast high-density applications. One consistent challenge in spintronics is electrical control of the magnetisation. Here, You et al demonstrate switching of magnetisation in a heterostucture composed of Mn3SnN and Permalloy, making use of the out-of-plane spin polarization induced by currents in the antiferromagnetic Mn3SnN. [ABSTRACT FROM AUTHOR]

Magnetic field dependence of the electronic spin polarization (P), polarization decay and spin oscillation in gallium arsenide quantum wells is investigated by spin-resolved photoluminescence measurements. In the presence of a magnetic field in the Voigt configuration, the spin-polarized electrons, generated by a circularly polarized light, are drifted by an electric field. The results show that P decays and oscillates with time as well as with the magnetic field. However, the electric field is found to play a vital role in spin dynamics and exchange coupling between the electron and hole spins in the wells. [ABSTRACT FROM AUTHOR]

Spin-polarized currents are investigated in symmetric (asymmetric) resonant magnetic tunnel junctions (S- (A)-RMTJs) including a non-magnetic metal (NM) layer. Charge-diode and spin-diode features are found for the S-RMTJs at definite thicknesses of MgO and NM layers. Owing to the presence of quantum-well states, a full spin polarization can be achieved by proper choice of the thickness of NM layer. The charge and spin currents have increased for the A-RMTJs in comparison to those of the S-RMTJs due to different properties of ferromagnetic electrodes. The present study suggests new spin-filter devices to use in the spintronics field. [ABSTRACT FROM AUTHOR]

We predicted the electronic structure and half-metallic properties of the Mn2XSb (X = Co, Fe) inverse Heusler alloys using the full-potential linearized augmented plane wave (FPLAPW) method. We used generalized gradient approximation (GGA) and GGA + U schemes to compute the electronic structure for both alloys. We employed the Tran and Blaha modified Becke–Johnson (TB-mBJ) potential to accurately estimate the band gap. The stability has been determined by calculating their formation energy and elastic constants under ambient conditions. Both alloys show a half-metallic ferromagnetic nature with a 100% spin polarization at the Fermi level. The calculated total spin magnetic moments of Mn2XSb (X = Co, Fe) alloys are 4 μ B and 3 μ B , respectively, which is a good agreement with the well-known Slater–Pauling rule of 24. The predicted Curie temperature for both alloys is greater than room temperature. The half-metallic and high spin polarization properties make them one of the promising candidates for spintronic device applications. [ABSTRACT FROM AUTHOR]

Taking into account the electron spin mobility, the paper considers the numerical solution to the equation for nonequilibrium spin polarization at the boundary of a magnetic contact with a current formed by two ferromagnets. The frequencies of spin injection radiation are calculated. It is shown that at a certain current density exceeding the threshold value, these frequencies lie in the terahertz frequency range. It was found that for the same terahertz frequency range, even for small values of the difference in the mobility of electrons with spin up and down, the current density can be two orders of magnitude lower than the current density with the same mobility. [ABSTRACT FROM AUTHOR]

The ultrafast demagnetization effect allows for the generation of femtosecond spin current pulses, which is expected to extend the fields of spin transport and spintronics to the femtosecond time domain. Thus far, directly observing the spin polarization induced by spin injection on the femtosecond time scale has not been possible. Herein, we present time- and spin-resolved photoemission results of spin injection from a laser-excited ferromagnet into a thin gold layer. The injected spin polarization is aligned along the magnetization direction of the underlying ferromagnet. Its decay time depends on the thickness of the gold layer, indicating that transport as well as storage of spins are relevant. This capacitive aspect of spin transport may limit the speed of future spintronic devices. [ABSTRACT FROM AUTHOR]

Electrical injection of spin-polarized electrons from ferromagnets into semiconductors has been generally demonstrated through a tunneling process with insulator barrier layers that can dominate the device performance, including the electric power at the electrodes. Here, we show an efficient spin injection technique for a semiconductor using an atomically controlled ferromagnet/ferromagnet/semiconductor heterostructure with low-resistive Schottky-tunnel barriers. On the basis of symmetry matching of the electronic bands between the top highly spin-polarized ferromagnet and the semiconductor, the magnitude of the spin signals in lateral spin-valve devices can be enhanced by up to one order of magnitude compared to those obtained with conventional ferromagnet/semiconductor structures. This approach provides a new solution for the simultaneous achievement of highly efficient spin injection and low electric power at the electrodes in semiconductor devices, leading to novel semiconductor spintronic architectures at room temperature. Spintronics: Increasing efficiency with a dose of iron Atomically precise deposition techniques can reduce the power demands of devices that use electron spins for high-speed and low-power computing. Spintronic systems often rely on quantum mechanical tunneling to move electrons with specific spins from magnets to semiconductors, but this process requires significant electrical energy. Kohei Hamaya from Osaka University in Toyonaka, Japan, and colleagues now report that these tunneling barriers can be tweaked by growing iron films only a few atomic layers thick between magnets and semiconductors. The team's studies revealed that the ultrathin films modified the energy levels in the interface region, creating an easy-to-access tunneling route for spin-polarized current. Because the iron atoms removed the need for insulating materials typically used in tunnel junctions, the device could operate at power levels an order of magnitude lower than usual. We show an efficient spin injection technique for a semiconductor using an atomically controlled ferromagnet/ferromagnet/semiconductor heterostructure with low-resistive Schottky-tunnel barriers. Even for semiconductor spintronic devices, the symmetry matching of electronic bands between the ferromagnet and the semiconductor should be considered. This approach provides a new solution for the simultaneous achievement of highly efficient spin injection and low electric power at the electrodes in semiconductor devices at room temperature. [ABSTRACT FROM AUTHOR]

An original equation for nonequilibrium spin polarization in magnetic junctions based on dynamic equations for magnetic moment was obtained. Spatial nonuniformity of the distribution of carriers is taken into account in the equations, and the magnetic moment is averaged over the ensemble of nonequilibrium spin-injected electrons. The solution to the dynamic equations for the magnetic moment is used to estimate the probability of spin-flip electron transitions upon spin injection, and the solution to the equation for the nonequilibrium spin polarization in magnetic junctions is used to calculate frequencies of photon emission or absorption at energies corresponding to the energy of effective exchange splitting of spin subbands. [ABSTRACT FROM AUTHOR]

The first principles calculations are carried out to understand the half metallic and ferromagnetic properties of Fe2−xCoxTiSi (x = 0, 0.5, 1, 1.5, 2) full Heusler alloys. The stable structure is predicted as L21 structure (Cu2MnAl phase). The lattice constant value of Fe2−xCoxTiSi Heusler compounds increases as the value of x increases. These alloys exhibit half metallic ferromagnetism (except Fe2TiSi) with small spin flip gap at the minority spin state. At high pressure, semiconductor to metallic phase transition is observed in Fe2TiSi while half metallic to metallic phase transition is observed in Fe1.5Co0.5TiSi, Fe1.0 Co1.0TiSi, Fe0.5Co1.5TiSi and Co2TiSi. The spin polarization of these compounds (except Fe2TiSi) is 100%. Hence, these compounds are suitable for spin injection devices in spintronics. [ABSTRACT FROM AUTHOR]

In this paper, we theoretically investigate how to control electron-spin polarization by δ-doping in a both magnetically and electrically confined semiconductor heterostructure. It is shown that, due to Zeeman coupling, a considerable spin polarization effect appears in the δ-doped device. It is also shown that both magnitude and sign of spin polarization can be tuned by changing weight or position of the δ-doping. Thus, a δ-doping controllable spin filter can be achieved for spintronics device applications. [ABSTRACT FROM AUTHOR]

The use of spontaneous electron spin polarization in nonmagnetic semiconductors avoids the transport challenges of electron spin injection from magnetic materials as well as packing constraints of small magnets in a dense array. Although the focus of rearch on the spontaneous spin polarization of electrical current has been on spin-orbit fields and their effects, in principle a moving electron gas can be unstable to forming spin-polarized distributions via carrier scattering processes that are independent of the carrier spin. The two required elements for such current-induced spin polarization without spin-orbit interactions are (1) the presence of built-in spatially-varying electric fields, either naturally forming (as in the Gunn effect) or extrinsic (as in a junction with spatially dependent doping) and (2) energy-dependent carrier scattering processes. As spin-orbit interactions are not required for this effect, it should occur in inversion-symmetric materials like silicon that lack zero-field spin splittings and materials like zinc oxide and gallium nitride that lack significant spin-orbit interactions. [ABSTRACT FROM AUTHOR]

The intermetallic compound Mn5Ge3 is one of the promising materials for application as a source of charge carriers in spintronics. The existing experimental data on the spin polarization in Mn5Ge3 demonstrate significant discrepancies. All theoretical studies concern a Mn5Ge3 bulk crystal. At the same time, thin films are of interest for applications. In this work, ab initio calculations have been performed for a Mn5Ge3 thin film on a germanium substrate. The difference between the magnetic moments of manganese atoms, densities of states, and spin polarizations for the bulk crystal and thin film has been demonstrated. [ABSTRACT FROM AUTHOR]

The degradation of polymer materials plays an important role in production and life. In this work, the degradation mechanism of poly-α-methylstyrene (PAMS) tetramers with abnormal linkage was investigated by using density functional theory (DFT). Calculated results indicate that the head-to-head and the tail-to-tail reactions needed to overcome the energy barriers are about 0.15 eV and about 1.26 eV, respectively. The broken C-C bond at the unsaturated end of the chain leads to the dissociation of alpha-methylstyrene (AMS) monomers one by one. Furthermore, the analyses of bond characteristics are in good agreement with the results of energy barriers. In addition, the spin population analysis presents an interesting net spin transfer process in depolymerization reactions. We hope that the current theoretical results provide useful help to understand the degradation mechanism of polymers. [ABSTRACT FROM AUTHOR]

The structural, electronic, and magnetic properties of new quaternary RhFeTiZ (Z = Al, Si) Heusler alloys were investigated, using the first-principle full-potential linearized-augmented plane wave (FP-LAPW) method with both generalized gradient approximation with Hubbard term U (GGA + U) and GGA + U plus modified Beck-Johnson (GGA + U + mBJ) exchange potentials. The RhFeTiZ (Z = Al, Si) compounds are stable in the ferromagnetic type I structure. The electronic and magnetic properties of RhFeTiZ (Z = Al, Si) compounds were calculated with GGA + U and improved with GGA + U + mBJ potential in the stable type I structure. We found that RhFeTiAl is a conventional semiconductor for both GGA + U and GGA + U + mBJ potential, whereas the RhFeTiSi is a nearly half-metallic for GGA + U and exhibits a half-metallic ferromagnetic behavior with spin polarization of 100 % for GGA + U + mBJ potential. The total magnetic moments are 0 and 1 μ for RhFeTiAl and RhFeTiSi, respectively, which are in agreement with the Slater-Pauling rule. Therefore, the RhFeTiSi seems to be a potential candidate for spintronic applications. [ABSTRACT FROM AUTHOR]

The electronic, structural, magnetic and transport properties of FeVTiAl quaternary alloy have been investigated within the framework of density functional theory. The material is a completely spin-polarized half-metallic ferromagnet in its ground state with F-43m structure. The structural stability was further confirmed by elastic constants in the cubic phase with high Young's modulus and brittle nature. The present study predicts an energy band gap of 0.72 eV in a localized minority spin channel at equilibrium lattice parameter of 6.00 Å. The transport properties of the material are discussed based on the Seebeck coefficient, and electrical and thermal conductivity coefficients. The alloy presents large values of Seebeck coefficients, ~39 μV K at room temperature (300 K), and has an excellent thermoelectric performance with ZT = ~0.8. [ABSTRACT FROM AUTHOR]

Within the framework of density functional theory, the electronic structure and magnetic properties have been studied for the LiXCl (X = V, Mn, Co and Fe) Suzuki-type compounds. Features such as the lattice constant and the bulk modulus and its pressure derivative are reported. The LiXCl (X = V, Mn, Co and Fe) Suzuki-type compounds show half-metallic ferromagnetism with total magnetic moments ( M ) of 3, 5, 3, and 4 μ per formula unit, respectively. The half metallicity is originated by the hybridization of TM-d states with Cl-p states. The analysis of charge density contours leads us to conclude that the bonding character in these compounds is a mixture between covalent and ionic natures. The half-metallic nature and complete 100 % spin polarization show that the new compounds have a potential application in spintronic devices. [ABSTRACT FROM AUTHOR]

The frequency tuning of the terahertz radiation of spin-injection oscillator based on magnetic contact junction that is formed by contacting ferromagnetic metal layers with different magnetizations is analyzed. Under the current-induced spin injection from one magnetic layer (injector) to another (working) layer, the interval of radiation frequencies is determined by the current density in the magnetic contact, the mismatch angle of the magnetizations of injector and working layer, and the equilibrium spin polarization. The wide-range tuning of terahertz frequencies of the spin-injection radiation can be implemented using variations in the above parameters. [ABSTRACT FROM AUTHOR]

A first-principles study on the electronic structure and magnetic properties of the RuZrSb Heusler compound has been performed by using the self-consistent full-potential linearized augmented plane wave (FPLAPW) method. It is found that the AlCuMn-type structure exhibits half-metallic ferrimagnetism and is preferable energywise than the CuHgTi-type structure. The total spin magnetic moment is based on mainly the Ru atoms and obeys the Slater-Pauling rule. The calculated total magnetic moment of RuZrSb is −1.0 μ at the equilibrium lattice constant 6.497 Å for the AlCuMn-type structure. The spin-down electrons are metallic, but the spin-up bands are semiconductor with a gap of 0.388 eV, and the spin-flip gap is 0.313 eV. The AlCuMn-type RuZrSb Heusler compound keeps a 100 % of spin polarization for lattice constants ranging between 6.40 and 6.53 Å. The Curie temperature is estimated to be 322.7 K in the mean field approximation (MFA). [ABSTRACT FROM AUTHOR]

A first-principles study of the electronic structure and magnetic properties of the Heusler compound Mn NbAl has been performed. The calculations have been performed by using the self-consistent full-potential linearized augmented plane wave (FPLAPW) method. It is found that the AlCu Mn-type structure is preferable energy wise than the CuHg Ti-type structure and exhibits half-metallic ferrimagnetism. The calculated total magnetic moment of Mn NbAl is 2 μ at the equilibrium lattice constant of 6.005 Å for the AlCu Mn-type structure. The total spin magnetic moment obeys the Slater-Pauling rule and is based on mainly the Mn atoms. The spin-down electrons are metallic, but the spin-up bands are semiconductor with a gap of 0.37 eV, and the spin-flip gap is of 0.09 eV. The AlCu Mn-type Mn NbAl full-Heusler compound keeps 100 % of spin polarization for lattice constants ranging between 5.93 and 6.20 Å. The Curie temperature is estimated to be 994 K in the mean field approximation (MFA). [ABSTRACT FROM AUTHOR]

Molecular semiconductors may exhibit antiferromagnetic correlations well below room temperature. Although inorganic antiferromagnetic layers may exchange bias single-molecule magnets, the reciprocal effect of an antiferromagnetic molecular layer magnetically pinning an inorganic ferromagnetic layer through exchange bias has so far not been observed. We report on the magnetic interplay, extending beyond the interface, between a cobalt ferromagnetic layer and a paramagnetic organic manganese phthalocyanine (MnPc) layer. These ferromagnetic/organic interfaces are called spinterfaces because spin polarization arises on them. The robust magnetism of the Co/MnPc spinterface stabilizes antiferromagnetic ordering at room temperature within subsequent MnPc monolayers away from the interface. The inferred magnetic coupling strength is much larger than that found in similar bulk, thin or ultrathin systems. In addition, at lower temperature, the antiferromagnetic MnPc layer induces an exchange bias on the Co film, which is magnetically pinned. These findings create new routes towards designing organic spintronic devices. [ABSTRACT FROM AUTHOR]

Spintronics utilizes spin or magnetism to provide new ways to store and process information and is primarily associated with the utilization of spin polarized currents in memory and logic devices. With the end of silicon transistor technology in sight, spintronics can provide new paradigms for information processing and storage. Compared to charge based electronics, the advantages of magnetism/spin based devices are nonvolatility and ultra low power. In particular, magnetoresistive random access memories (MRAMs) are known to be “Rad Hard” [HXNV0100 64K x 16 Non-Volatile Magnetic RAM (www.honeywell.com/aerospace), S. Gerardin and A. Paccagnella, IEEE Trans. Nucl. Sci.57(6), 3016–3039 (2010), R.R. Katti, J. Lintz, L. Sundstrom, T. Marques, S. Scoppettuolo, and D. Martin, Proceedings of IEEE Radiation Effects Data Workshop, 103–105 (2009)] and are considered to be critical components for space and military systems due to their very low power consumption and nonvolatility. However, advances in the magnetic nanostructures and new materials for the scalability of MRAM and other potential applications require a re-evaluation of their radiation hardness. This review focuses mainly on recent progress in understanding the effects of irradiation on the magnetic materials and magnetic structures that are related to MRAM technology. Up to date, the most pronounced effects on the microstructures and the properties are linked to the displacement damage associated with heavy ion irradiation; however, the thermal effect is also important as it acts as an annealing process to recover the damage partially. Critical metrics for the magnetic tunnel junctions for postmortem characterizations will also be discussed. Finally, with the introduction of new perpendicular magnetic layers and the very thin MgO barrier layer in the next generation MRAM, the effects of the ionization damage shall be studied in the future. [ABSTRACT FROM PUBLISHER]

The polarization characteristics of doped spin-injected quantum dot vertical cavity surface emitting laser (QD-VCSEL) have been studied using multi-population spin-flip coupled rate equation model. The stability conditions of spin-injected VCSEL are also investigated for different device parameters. Our analysis reveals that QD-VCSEL emitting at high lasing energies, close to the first excited state energy, demonstrates high output ellipticity and high ellipticity gain compared to QD-VCSEL emitting at the ground state energy. Also, we find that increasing the p-type doping concentration of the quantum dots increases the output ellipticity gain of the device and significantly alters the stability conditions of the VCSEL. Large instability is observed when the VCSEL is emitting near $$\sim \!\!70\hbox {meV}$$ above the ground state energy and when the quantum dots are doped with $$\sim \!\!4\times 10^{10}\,\hbox {cm}^{-2}$$ of p-type concentration. Moreover, we find that QD-VCSEL exhibits good stability when its emission energy is approximately 10-20 meV higher than the ground state energy and when the dots are doped with more than $$4\times 10^{10}\,\hbox {cm}^{-2}$$ of p-type concentration. [ABSTRACT FROM AUTHOR]

We analyze the electronic structure of interfaces between two-, four- and six-layer Gd(0001) and monolayer MoS2 by first-principles calculations. Strong chemical bonds shift the Fermi energy of MoS2 upwards into the conduction band. At the surface and interface the Gd f states shift to lower energy and new surface/ interface Gd d states appear at the Fermi energy, which are strongly hybridized with the Mo 4d states and thus lead to a high spin-polarization (ferromagnetically ordered Mo magnetic moments of 0.15 μB). Gd therefore is an interesting candidate for spin injection into monolayer MoS2. [ABSTRACT FROM AUTHOR]

The interconversion of charge and spin currents via spin-Hall effect is essential for spintronics. Energy-efficient and deterministic switching of magnetization can be achieved when spin polarizations of these spin currents are collinear with the magnetization. However, symmetry conditions generally restrict spin polarizations to be orthogonal to both the charge and spin flows. Spin polarizations can deviate from such direction in nonmagnetic materials only when the crystalline symmetry is reduced. Here, we show control of the spin polarization direction by using a non-collinear antiferromagnet Mn3GaN, in which the triangular spin structure creates a low magnetic symmetry while maintaining a high crystalline symmetry. We demonstrate that epitaxial Mn3GaN/permalloy heterostructures can generate unconventional spin-orbit torques at room temperature corresponding to out-of-plane and Dresselhaus-like spin polarizations which are forbidden in any sample with two-fold rotational symmetry. Our results demonstrate an approach based on spin-structure design for controlling spin-orbit torque, enabling high-efficient antiferromagnetic spintronics. In the typical spin-hall effect, spin-current, charge current, and spin polarisation are all mutually perpendicular, a feature enforced by symmetry. Here, using an anti-ferromagnet with a triangular spin structure, the authors demonstrate a spin-hall effect without a perpendicular spin alignment. [ABSTRACT FROM AUTHOR]

Fine-tuning of magnetic states via an understanding of spin injection on the edge of graphene nanoribbons should allow for greater flexibility of the design of graphene-based spintronics. On the basis of calculations, we predict that coupling constants of the exchange interaction in the series of nitroxide-functionalized ribbon compounds are antiferromagnetic across the ribbons with values 0.2–0.4 cm−1 and ferromagnetic along the ribbon with absolute values from 0.05 to 0.07 cm−1. Such interacting nitroxide groups induce spin polarization of the edge states of stable graphene nanoribbons. Graphical abstract Exchange coupling constants inducing spin polarization in graphene nanoribbons functionalized with nitroxides. [ABSTRACT FROM AUTHOR]

With the purpose of searching for new intriguing nanomaterial for spintronics, a series of novel metalloporphyrin nanowires (M-PPNW, M = Cr, Mn, Fe, Co, Ni, Cu and Zn) and hybrid nanowires fabricated by metalloporphyrin and metal-phthalocyanine (M-PCNW) are systematically investigated by means of first-principles calculations. Our results indicate that the transition metal atoms (TMs) embedded in the frameworks distribute regularly and separately, without any trend to form clusters, thus leading to the ideally ordered spin distribution. Except for the cases embedded with Ni and Zn, the others are spin-polarized. Remarkably, the Mn-PPNW, Mn-PCNW, MnCu-PPNW, MnCr-PCNW, and MnCu-PCNW frameworks all favor the long-ranged ferromagnetic spin ordering and display half-metallic nature, which are of greatest interest and importance for electronics and spintronics. The predicted Curie temperature for the Mn-PCNW is about 150 K. In addition, it is found that the discrepancy in magnetic coupling for these materials is related to the competition mechanisms of through-bond and through-space exchange interactions. In the present work, we propose not only two novel sets of 1D frameworks with appealing magnetic properties, but also a new strategy in obtaining the half-metallic materials by the combination of different neighboring TMs. [ABSTRACT FROM AUTHOR]

We report a first-principle study on electronic structure and simulation of the spin-polarized scanning tunneling microscopy graphic of a benzene/Fe4N interface. Fe4N is a compound ferromagnet suitable for many spintronic applications. We found that, depending on the particular termination schemes and interface configurations, the spin polarization on the benzene surface shows a rich variety of properties ranging from cosine-type oscillation to polarization inversion. Spin-polarization inversion above benzene is resulting from the hybridizations between C pz and the out-of-plane d orbitals of Fe atom. [ABSTRACT FROM AUTHOR]

Ultraviolet photoemission spectroscopy (UPS) is a powerful tool to study the electronic spin and symmetry features at both surfaces and interfaces to ultrathin top layers. However, the very low mean free path of the photoelectrons usually prevents a direct access to the properties of buried interfaces. The latter are of particular interest since they crucially influence the performance of spintronic devices like magnetic tunnel junctions (MTJs). Here, we introduce spin-resolved extremely low energy photoemission spectroscopy (ELEPS) to provide a powerful way for overcoming this limitation. We apply ELEPS to the interface formed between the half-metallic Heusler compound Co2MnSi and the insulator MgO, prepared as in state-of-the-art Co2MnSi/MgO-based MTJs. The high accordance between the spintronic fingerprint of the free Co2MnSi surface and the Co2MnSi/MgO interface buried below up to 4 nm MgO provides clear evidence for the high interface sensitivity of ELEPS to buried interfaces. Although the absolute values of the interface spin polarization are well below 100%, the now accessible spin- and symmetry-resolved wave functions are in line with the predicted existence of non-collinear spin moments at the Co2MnSi/MgO interface, one of the mechanisms evoked to explain the controversially discussed performance loss of Heusler-based MTJs at room temperature. [ABSTRACT FROM AUTHOR]