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A mesoscopic multi-terminal superconducting Nb strip with a spin injection terminal has been developed. We investigate the influence of the spin polarization on the relaxation process of the quasiparticle in the superconducting Nb. The position dependence of the nonlocal voltage provides the quasiparticle relaxation length. The relaxation length for the spin-polarized quasiparticle is found to show 12.5 percent increase from that for the un-polarized quasiparticle. This demonstration opens a new avenue for utilization of the the spin current in a superconducting device.

Out-of-plane spin polarization {\sigma}_z 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{\deg} triangular spin configuration, has been discovered to possess {\sigma}_z. However, the physical origin of {\sigma}_z in noncollinear AFM is still not clear, and the external magnetic field-free switching of perpendicular magnetic layer using the corresponding {\sigma}_z has not been reported yet. Here, we use the cluster magnetic octupole in antiperovskite AFM Mn3SnN to demonstrate the generation of {\sigma}_z. {\sigma}_z 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 {\sigma}_z, 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., Comment: 23 pages, 4 figures, accepted by Nat. Commun

Nodal monoloop, enjoying the cleanest scenario with a single loop, is recognized as the basic building block of intricate linked loops including chains, nets, and knots. Here, we explore the interplay of magnetic ordering and band topology in one system by introducing a brand-new quantum state, referred to as Weyl monoloop semi-half-metal, which is characterized by a single loop at the Fermi level stemming from the same spin channel. Such a nodal line Fermion, yielding 100% spin polarization, is protected by mirror ( M z ) symmetry. As a prominent example, a realistic rutile-type metal fluorides LiV2F6 achieves the hitherto unmaterialized state, featuring fully spin-polarized ultraflat surface states. More interestingly, LiV2F6 has a "soft" ferromagnetic property, which is one of the desired systems to control the anomalous Hall effect by rotating the magnetization direction. Our findings offer a promising candidate for exploring the topology and magnetism with intriguing effects.

In this article, for the first time, we propose a silicene-based spin filter having a TFET configuration. The device portrays a voltage-dependent spin polarization and achieves a “spin polarization” as high as 98% at a minimal “operating voltage” (0.35 V). The operation of the device is based on the “spin-polarized edge states” in a silicene nanoribbon. The “spin polarization” of the output current can be tuned by modifying the bandgap of the spin-up and spin-down states via an in-plane perpendicular “electric field” generated by two “lateral gates.” The device features high spin polarization apart from its expected integration with Si-based technology. The proposed device has a simple construction, wherein a single layer of Si atoms achieves such a high value of spin polarization at a minimal operating voltage. The operation of the proposed device is demonstrated by using the first-principles quantum transport simulations.

International audience; The nitrogen-vacancy (NV) center in 3C-SiC, the analog of the NV center in diamond, has recently emerged as a solid-state qubit with competitive properties and significant technological advantages. Combining first-principles calculations and magnetic resonance spectroscopy we provide thorough insight in its magneto-optical properties. By applying resonantly excited electron paramagnetic resonance spectroscopy, we identified the zero-phonon absorption line of the 3 A 2 → 3 E transition at 1289 nm (within the telecom Oband) and measured its phonon sideband, the analysis of which reveals a Huang-Rhys factor of S = 2.85 and a Debye-Waller factor of 5.8 %. The low temperature spin-lattice relaxation time was found to be exceptionally long (T 1 = 17 s at 4 K). All these properties make NV in 3C-SiC a strong competitor for qubit application. In addition, the strong variation of the zero-field splitting in the range of 4K to 380K allows its application for nanoscale thermal sensing.

In this paper, we present the results obtained from our study on the heat current across double quantum dots in serial coupled to ferromagnetic leads (FM-DQDs-FM), when the leads magnetic moments are in antiparallel configuration. This study was done by using nonequilibrium Green's function method in the linear response regime. Our results are calculated in weak interdot coupling regime by taking all the parameters that affect the system such as intradot Coulomb correlation energy, spin–spin exchange interaction, and spin polarization on the leads. These results are accomplished as a function of temperature gradient as well as quantum dots energy levels. According to our results, it is noticed that the values of intradot Coulomb correlation energy and the spin–spin exchange interaction have significant impact on increasing the heat current that flows through our system. It is concluded that increasing or decreasing the magnitude of heat current in negative or positive thermal bias is ideal for designing high-efficiency heat diode.

The first-principle calculations of density functional theory were used to study the structural, electronic, magnetic, mechanic, and half-metallic behavior of Y2MnZ (Z = Al, Ga, In) within the spin generalized gradient approximation. These compounds can be experimentally synthesized due to their negative values of the calculated formation energies. Our calculations indicate that they are more stable in Cu2MnAl-type structure. The Hg2CuTi-type structure displays half-metallic characteristic with 100% spin polarization at the Fermi level. The value of calculated magnetic moment has an integer value of 2μB for Y2MnZ (Z = Al, Ga, In) in the Hg2CuTi-type structure which well matches with magnetic moments predicted from Slater–Pauling rule. Therefore, the Y2MnZ (Z = Al, Ga, In) in the Hg2CuTi-type structure is predicted to be a candidate for possible spintronics applications.

A change in the sign of the ground-state electron spin polarization (ESP) is reported in complexes where an organic radical (nitronylnitroxide, NN) is covalently attached to a donor–acceptor chromophore via two different meta-phenylene bridges in (bpy)Pt(CAT-m-Ph-NN) (mPh-Pt) and (bpy)Pt(CAT-6-Me-m-Ph-NN) (6-Me-mPh-Pt) (bpy = 5,5′-di-tert-butyl-2,2′-bipyridine, CAT = 3-tert-butylcatecholate, m-Ph = meta-phenylene). These molecules represent a new class of chromophores that can be photoexcited with visible light to produce an initial exchange-coupled, 3-spin (bpy˙−, CAT+˙ = semiquinone (SQ), and NN), charge-separated doublet 2S1 (S = chromophore excited spin singlet configuration) excited state. Following excitation, the 2S1 state rapidly decays to the ground state by magnetic exchange-mediated enhanced internal conversion via the 2T1 (T = chromophore excited spin triplet configuration) state. This process generates emissive ground state ESP in 6-Me-mPh-Pt while for mPh-Pt the ESP is absorptive. It is proposed that the emissive polarization in 6-Me-mPh-Pt results from zero-field splitting induced transitions between the chromophoric 2T1 and 4T1 states, whereas predominant spin–orbit induced transitions between 2T1 and low-energy NN-based states give rise to the absorptive polarization observed for mPh-Pt. The difference in the sign of the ESP for these molecules is consistent with a smaller excited state 2T1 – 4T1 gap for 6-Me-mPh-Pt that derives from steric interactions with the 6-methyl group. These steric interactions reduce the excited state pairwise SQ-NN exchange coupling compared to that in mPh-Pt., A change in the sign of the ground state electron spin polarization (ESP) is reported in complexes where an organic radical (nitronylnitroxide, NN) is covalently attached to a donor–acceptor chromophore via two different meta-phenylene bridges.

Three different contributing mechanisms have been considered to calculate the magnetization (M) of p-type Pb1-xMnxSe for a hole density of p = 5 × 1018 cm−3and n-type Pb1-xMnxS for an electron density of n = 6 × 1018 cm−3.The first mechanism comes from the valence band diamagnetism which is calculated in a frame of the two-band model. The second mechanism which we consider arises from the spin densities of holes and electrons and we use a six-level $$\vec{k}.\vec{\pi }$$ theory in second-order perturbation theory in the effective mass representation. The third mechanism is the impurity Mn+2 ions contribution, and we consider small clusters consisting of one, two and three spins to evaluate it. The three spin clusters include both open and closed types. It has been observed that the former two mechanisms contribute very little to the magnetization compared to the latter one. However, their importance cannot be ignored because they provide a deeper understanding of the underlying physical mechanisms involved with carrier spin polarization and orbital diamagnetism of the host matrix, in which the Mn+2 spins are embedded. Good agreement of our theory with experiment is the other interesting and distinct feature of this work.

A new scheme is presented for obtaining a pure spin state for the one-determinant wave function built on Hartree–Fock or Kohn–Sham orbitals. In this scheme, the unrestricted determinant is expanded in restricted determinants constructed in the basis set of spin-paired orbitals. Using spin projection, one can determine spin density components corresponding to pure spin states and estimate the weight of spin contaminants in the spin density. The efficiency of this approach is demonstrated on the example of methane oxidation. It is shown that self-consistent solutions of Hartree–Fock or Kohn–Sham equations with broken spin symmetry are not an artifact of one-determinant approximation. The equations reflect real spin polarization that creates negative spin density in some parts of the molecular system.

Electric field control of magnetic properties has been achieved across a number of different material systems. In diluted magnetic semiconductors (DMSs), ferromagnetic metals, multiferroics, etc., electrical manipulation of magnetism has been observed. Here, we study the effect of an electric field on the carrier spin polarization in DMSs ( GaAsMn ); in particular, emphasis is given to spin-dependent transport phenomena. In our system, the interaction between the carriers and the localized spins in the presence of electric field is taken as the main interaction. Our results show that the electric field plays a major role on the spin polarization of carriers in the system. This is important for spintronics application.

We systematically analyze the effects of the derivatives of the hydrodynamic fields on axial Wigner function that describes the spin polarization vector in phase space. We have included all possible first-order derivative contributions that are allowed by symmetry and compute the associated transport functions at one-loop using the linear response theory. In addition to reproducing known effects due to the temperature gradient and vorticity, we have identified a number of potentially significant contributions that are overlooked previously. In particular, we find that the shear strength, the symmetric and traceless part of the flow gradient, will induce a quadrupole for spin polarization in the phase space. We refer to this novel effect as the shear-induced polarization (SIP). Our results, together with hydrodynamic gradients obtained from hydrodynamic simulations, can be employed as a basis for the interpretation of the $\Lambda$ (anti-$\Lambda$) spin polarization measurement in heavy-ion collisions., Comment: 18 pages, 2 figures, matched to the published version

Hyperons production and decays are studied with using 1310.6 × 106 J/ψ and 448.1 × 106 ψ(3686) events collected with the BESIII experiment. The recent achievements in BESIII are report. The spin polarization of Σ+ and Σ ‾ − is observed in J/ψ and ψ(3686) decays for the first time. The spin of Ω− is determined to be 3/2 unambiguously with helicity amplitude analysis method. The SU(3)-flavor violating decay J / ψ → Ξ ( 1530 ) − Ξ ‾ + + c.c. is studied with the evidence for the radiative decay Ξ(1530)− → γΞ− of a significance of 3.9σ. The branching fractions of the decays χ c J → Σ − Σ ‾ + are measured for the first time using the final states n n ‾ π + π − .

The linear properties of magnetosonic waves are studied by using the separated spin evolution quantum hydrodynamic equations in which each electron and positron are treated as two different fluids. At the perpendicular propagation, we have only one magnetosonic wave which is affected by both spin polarization and concentration of positron. In the case of oblique propagation, we solve dispersion numerically and found that three wave solutions are obtained without taking into account separate spin evolution (SSE), but the oblique propagation with SSE gives five wave solutions, two of them are electron and positron spin-dependent wave solutions and have been reported for the first time. It is noted that the spin polarization and positron concentration reduce the phase velocities of the obliquely propagating spectra. Moreover, it is seen that the obliqueness effect enhances the frequency of all waves. Finally, the comparison with earlier reported results is also presented. For numerical analysis, we choose parameters relevant to astrophysical environments.

We theoretically investigate the dwell time for electrons in an antiparallel double $\delta $ -magnetic-barrier nanostructure, which is constructed on the surface of the InAs/Al x In1- x As heterostructure by patterning two ferromagnetic (FM) stripes. It is shown that the dwell time is dependent on electron spins due to the spin–field interaction between spins and magnetic fields. It is also shown that both magnitude and sign of the spin polarization in the dwell time can be modulated by the structural width or magnetic-strength difference between two magnetic barriers, which may give rise to a controllable temporal spin splitter for spintronics device applications.

Non-stationary spin-dependent transport through the interacting single-level quantum dot coupled to ferromagnetic leads with non-collinear magnetizations has been analyzed theoretically. The non-stationary transport is investigated within the theoretical approach based on kinetic equations for the electron occupation numbers with different spins taking into account high order correlation functions for the localized electrons. It has been demonstrated that spin polarization, direction and amplitude of the non-stationary currents could be effectively changed in a rather simple system by varying the relative directions of the magnetic moments in the leads. The degree of the currents spin polarization also changes following the direction of magnetic moments in the leads. The results open a possibility for spin polarization control in nanoscale systems and are very promising in the sense of spin filtering.

We review recent studies of the spin-dependent tunneling transport via an Aharonov–Bohm interferometer (ABI) formed by helical edge states. We focus on the experimentally relevant case of relatively high temperature, T, as compared to level spacing, Δ. The tunneling conductance of helical ABI is structureless in ballistic case but shows sharp periodic antiresonances as a function of magnetic flux with the period $$hc{\text{/}}2e$$ in presence of magnetic impurities. The incoming unpolarized electron beam acquires finite polarization after transmission through the helical ABI provided that the edges contain at least one magnetic impurity. The finite polarization appears even in the fully classical regime and is therefore robust to dephasing. There is also a quantum contribution to the polarization, which shows sharp identical resonances as a function of magnetic flux with the same period as conductance. This polarization survives at relatively high temperature. The interferometer can be described in terms of ensemble of $$\mathcal{N} \simeq T{\text{/}}\Delta $$ flux-tunable qubits giving equal contributions to conductance and spin polarization. Hence, with increasing the temperature number of active qubits participating in the charge and spin transport increases. These features of tunneling helical ABI open a wide avenue for applications in the area of quantum computing.

We perform a first-principles calculation to understand the effect of the additional valence electron of the transition atom in Wyckoff position 4 a, on the electronic structure, magnetic and structural stability of the full Heusler $${\mathrm{Mn}}_{2}\mathrm{PtZ}(\mathrm{Z}=\mathrm{V and Co})$$ compound. L21, Xa and tetragonal structures are considered to verify the most stable phase. Within the framework of the plan $${\mathrm{Mn}}_{2}\mathrm{PtZ}(\mathrm{Z}=\mathrm{V and Co})$$ favored the ferromagnetic configuration in the L21 structure. The results show that the 63% and 91% spin polarization at the Fermi level for $${\mathrm{Mn}}_{2}\mathrm{PtV}$$ and $${\mathrm{Mn}}_{2}\mathrm{PtCo}$$ , respectively. The most contribution of the magnetic moment is due to the Mn atom, the total magnetic moments equal to $${4.87\upmu }_{\mathrm{B}}$$ and $${9.012\upmu }_{\mathrm{B}}$$ have been reported. To prove the half metallicity of our compound, we used the GGA + U approach. Within the framework of this approach, the value gap in the minority spin band is 0.755 eV, more, the magnetic moment satisfying the Slater-Pauling rule for the $${\mathrm{Mn}}_{2}\mathrm{PtV}$$ compound. In addition, we give the two values of the curie temperatures for the two cubic structural phases. Finally, both full Heusler $${\mathrm{Mn}}_{2}\mathrm{PtV}$$ and $${\mathrm{Mn}}_{2}\mathrm{PtCo}$$ are a promising candidate for the use of future devices as spin-FETs and nonvolatile magnetic memory.

To broaden the scope of van der Waals 2D magnets, we report the synthesis and magnetism of covalent 2D magnetic Cr$_2$Te$_3$ with a thickness down to one-unit-cell. The 2D Cr$_2$Te$_3$ crystals exhibit robust ferromagnetism with a Curie temperature of 180 K, a large perpendicular anisotropy of 7*105 J m-3, and a high coercivity of ~ 4.6 kG at 20 K. First-principles calculations further show a transition from canted to collinear ferromagnetism, a transition from perpendicular to in-plane anisotropy, and emergent half-metallic behavior in atomically-thin Cr$_2$Te$_3$, suggesting its potential application for injecting carriers with high spin polarization into spintronic devices.

The spin resonance of two-dimensional conduction electrons in a ZnO/MgZnO heterojunction in tilted magnetic fields is studied near the filling factor $$\nu = 2$$ . The analysis of the spin resonance intensity at various ν values indicates that a phase transition accompanied by drastic change in the spin polarization occurs in a two-dimensional electron system at a certain angle near $$\nu = 2$$ . For ν values larger than a certain critical value νc, an intense spin resonance is observed, clearly demonstrating that the system turns out to be in a spin-polarized state. For ν < νc, the resonance amplitude drops by more than an order of magnitude, and the spin polarization of the ground state decreases significantly. In the immediate vicinity of the transition, the spin resonance is broadened significantly and split into several independent peaks. Such behavior of the resonance can most likely be explained by the division of the system into domains with different spin polarizations.

In non-centrosymmetric metals, spin-orbit coupling (SOC) induces momentum-dependent spin polarization at the Fermi surfaces. This is exemplified by the valley-contrasting spin polarization in monolayer transition metal dichalcogenides (TMDCs) with in-plane inversion asymmetry. However, the valley configuration of massive Dirac fermions in TMDCs is fixed by the graphene-like structure, which limits the variety of spin-valley coupling. Here, we show that the layered polar metal BaMn$X_2$ ($X =$Bi, Sb) hosts tunable spin-valley-coupled Dirac fermions, which originate from the distorted $X$ square net with in-plane lattice polarization. We found that in spite of the larger SOC, BaMnBi$_2$ has approximately one-tenth the lattice distortion of BaMnSb$_2$, from which a different configuration of spin-polarized Dirac valleys is theoretically predicted. This was experimentally observed as a clear difference in the Shubnikov-de Haas oscillation at high fields between the two materials. The chemically tunable spin-valley coupling in BaMn$X_2$ makes it a promising material for various spin-valleytronic devices., Comment: 25 pages, 4 figures. Published in Communications Materials

The influence of spatial variation of Fermi velocity on the spin-polarized transport properties of massless Dirac fermions in proximity-induced ferromagnetic graphene junction was investigated. We found that the velocity ratio ξ causing the width of the spin conductance dip near the Dirac point is broadened as the Fermi velocity ratio increases. In contrast, the effect of the Fermi velocity mismatch does not affect the shifting of the Dirac point. It leads to the indirect measurement of the Fermi velocity ratio that can be tuned by the spin-dependent conductance. In addition to the presence of both the exchange field and the Fermi velocity modulation, we found high spin filtering occurs when the Fermi velocity ratio ξ ≥ 1. Due to the transmission probability of electron with spin down, T↓ is blocked by the effect of Fermi velocity modulation similar to waves travelling through a different media. Moreover, we also found that the resonant transmission of the electron with spin up can be perfectly transmitted through the Fermi velocity barrier at the limit injected angle θ → π/2 for H/EF ≈ 1. The spin transport properties can be controlled by suitably modifying the strength of the ferromagnetic insulator and varying the Fermi velocity modulation, which leads to the highest spin polarization. By manipulating the behavior of spin-dependent collimation and spin beam splitting in this structure, we proposed a spin transport device for making lateral spin polarization. These interesting features will help make the development of spintronic devices in the graphene-based nanostructure.

A comprehensive overview of the performance of local hybrid functionals for molecular properties like excited states, ionization potentials within the GW framework, polarizabilities, magnetizabilities, NMR chemical shifts, and NMR spin-spin coupling constants is presented. We apply the generalization of the kinetic energy, τ, with the paramagnetic current density to all magnetic properties and the excitation energies from time-dependent density functional theory. This restores gauge invariance for these properties. Different ansatze for local mixing functions such as the iso-orbital indicator, the correlation length, the Gorling-Levy second-order limit, and the spin polarization are compared. For the latter, we propose a modified version of the corresponding hyper-generalized gradient approximation functional of Perdew, Staroverov, Tao, and Scuseria (PSTS) [Phys. Rev. A2008, 78, 052513] to allow for a numerically stable evaluation of the exchange-correlation kernel and hyperkernel. The PSTS functional leads to a very consistent improvement compared to the related TPSSh functional. It is further shown that the "best" choice of the local mixing function depends on the studied property and molecular class. While functionals based on the iso-orbital indicator lead to rather accurate excitation energies and ionization energies, the results are less impressive for NMR properties, for which a considerable dependence on the considered molecular test set and nuclei is observed. Johnson's local hybrid functional based on the correlation length yields remarkable results for NMR shifts of compounds featuring heavy elements and also for the excitation energies of organic compounds.

Magnetic sensing based on nitrogen-vacancy (NV) centers in diamond have been considered by scientists to be a promising candidate for highly sensitive, integrated solid-state quantum sensors. In this paper, a displacement detection system is presented relying on the quantum magnetic effect of NV ensemble under a microwave (MW), which consists of a fluorescence microscope system and a bundle of movable current-carrying coils. The fluorescence microscope system is responsible for efficient fluorescence excitation and collection to identify the energy level splitting of electron spin. Moreover, the current-carrying coils are responsible for creating a gradient magnetic field with high linearity. Measurement by experiment, the theory sensitivity limit of the proposed device can up to 2.713 nm/Hz1/2, and the noise sensitivity is $51.93~\mu \text{m}$ /Hz1/2 when the coils carry the current 0.1 A. The response of fluorescence intensity (PL) to displacement can be up to 0.493%/mm for $\vert + 1\rangle $ sublevel with a measurement range of 12.57 mm and 0.419%/mm for $\vert - 1\rangle $ sublevel with a measurement range of 13 mm. Through experimental verification, the sensitivity and response can increase proportionally with the current, while the measurement range is inversely reduced. In view of this, the proposed displacement detection system can be used in displacement detection applications of different precision.

Topological aspects of the geometry of DNA and similar chiral molecules have received a lot of attention, while the topology of their electronic structure is less explored. Previous experiments have revealed that DNA can efficiently filter spin-polarized electrons between metal contacts, a process called chiral-induced spin-selectivity (CISS). However, the underlying correlation between chiral structure and electronic spin remains elusive. In this work, we reveal an orbital texture in the band structure, a topological characteristic induced by the chirality. We find that this orbital texture enables the chiral molecule to polarize the quantum orbital. This orbital polarization effect (OPE) induces spin polarization assisted by the spin-orbit interaction from a metal contact and leads to magnetorestistance and chiral separation. The orbital angular momentum of photoelectrons also plays an essential role in related photoemission experiments. Beyond CISS, we predict that OPE can induce spin-selective phenomena even in achiral but inversion-breaking materials., Comment: 24 pages, 4 figures, and Supplementary Materials

Silicene has attracted the research interest due to its excellent electronic and spin properties. Furthermore, CrO2 half metal due to its high Curie temperature and high spin polarization is well suited for electrodes. In this work, we have simulated the magnetic tunnel junction device consisting of CrO2 electrodes and Silicene as a scattering region. The device is in a sub 10-nm regime, hence supports high integration density. The bias dependent spin transport properties (I-V characteristics and transmission spectrum) of the modeled device were calculated by Atomistic Tool Kit software, which uses density functional theory and non-equilibrium Greens function formalism. The device shows large tunnel magnetoresistance of 640%, depicting the potential application of the proposed device. The spin-dependent transmission spectrum, band structure, semi-conductor theory has been discussed to explain the origin of the spin-dependent transport characteristics. Moreover, an efficient method for MRAM (magnetic random access memory) read/write operation has been discussed. Furthermore, a NAND gate from a single modeled MTJ device has been realized, a half adder has also been realized from the modeled device to explore the potential of the modeled device for the implementation of complex digital functions.

We investigate spin dependent electron transport through a magnetic helix (MH) which is coupled to one input and two output leads. Suitably adjusting the physical parameters and lead positions we can achieve high degree of spin polarizations with opposite phase at the output terminals. We consider both long-range and short-range hopping magnetic helices and critically examine the interplay between these hopping integrals on spin polarization. From our results we find that the long-range hopping MH is much superior than the short-range one. Simulating the quantum system within a tight-binding framework we compute spin dependent transmission probabilities and spin polarization co-efficient using the well known Green’s function formalism. Our proposition can provide a deeper impact in realizing efficient spin based devices in near future.