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First-principle calculations were used to simulate the changes in magnetic parameters and interatomic charge density in the crystal structure of yttrium iron garnet (YIG) caused by Ca–Sn co-doping. The simulation results illustrate that Ca and Sn have no spin polarization in the crystal, and the charge density among ions tends to increase with doping concentration. A solid-state reaction method was employed to prepare YIG with varying concentrations of Ca–Sn co-doping. The saturation magnetization ($4\pi M_{s}$) of the material shows an initial increase and then decrease as the number of doping increases. This phenomenon of increment in $4\pi M_{s}$ at first could be accounted for the increase of the net magnetic moment of material. The reduction in $4\pi M_{s}$ could be interpreted as the content of Fe3+ ($5~\mu \text{B}$) decreases, while the Fe2+ ($4~\mu \text{B}$) in the material becomes the primary portion when the concentration of doping exceeds 0.10. [ABSTRACT FROM AUTHOR]

In this article, we study the coupling of low-frequency electrostatic waves in the electron-ion and the electron-ion-beam-spin quantum plasmas. The quantum effect of electrons are introduced via separate spin evolution-quantum hydrodynamic (SSE-QHD) model while the ion dynamics is governed by classical fluid equations. In the case of electron-ion plasma, it is found that the quantum effects shift both the coupling domain and the phase velocities of coupled waves. Furthermore, the coupling is observed to be strong at small propagation angles. In the beam interacting system, two coupling domains occur corresponding to small and large $k$ -values. In the first domain beam mode excites the ion cyclotron (IC) wave and moves with constant phase velocity while in the second domain it gains energy from the ion acoustic (IA) mode and travels with increasing phase velocity. In addition, the beam parameters affect both the coupling domain and the phase velocity. The presence of beam in electron-ion plasma drives the IC mode unstable. The beam parameters, the spin, and the obliqueness affect the instability. Our findings may be helpful in understanding the energy exchange of plasma waves via coupling phenomenon in degenerate plasma systems. [ABSTRACT FROM AUTHOR]

A mesoscopic multi-terminal superconducting Nb strip with a spin injection terminal has been developed. We investigate the influence of 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 a 12.5% increase from that for the un-polarized quasiparticle. This demonstration opens a new avenue for utilization of the spin current in a superconducting device. [ABSTRACT FROM AUTHOR]

The results of the optical properties study and the electronic structure calculation of ${\text{Co}}_{2}Y\text {Si}$ ($Y = \text {Ti}$ , V, Cr, Mn, Fe) Heusler alloys are presented. Temperature dependences of the electrical resistivity were studied in the temperature range from 4.2 to 300 K. Field dependences of magnetization were measured in the magnetic fields of up to 5 T. The main attention is paid to the spectral dependence of the real and imaginary parts of the dielectric constant in the wavelength range from 0.3 to $8~\mu \text{m}$ by the ellipsometric Beattie method at room temperature. Anomalous behavior of optical conductivity at infrared (IR) frequencies in Co2TiSi and Co2VSi alloys was found, which significantly differs from that in Co2MnSi, Co2FeSi, and Co2CrSi. The results obtained are discussed based on calculations of the electronic structure. Simultaneously, the correlations between the changes in these characteristics can be an indicator of the states of a half-metallic ferromagnet (HMF) or a spin gapless semiconductor (SGS). A high degree of charge carriers’ spin polarization is possible in such materials, and therefore, they are promising materials for spintronics. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]