铁磁/ 反铁磁双层膜中交换偏置

铁磁/反铁磁交换偏置在巨磁电阻器件中具有重要的应用。引起了物理学及材料学等领域内广大科学家的浓厚兴趣，本文首先阐述了交换偏置的基本性质。然后简述了交换偏置的实验研究方法；最后，着重介绍了几种主要的理论模型。     

铁磁/反铁磁双层膜中交换偏置

铁磁 /反铁磁交换偏置在巨磁电阻器件中具有重要的应用 ,引起了物理学及材料学等领域内广大科学家的浓厚兴趣。本文首先阐述了交换偏置的基本性质 ;然后简述了交换偏置的实验研究方法 ;最后 ,着重介绍了几种主要的理论模型。     

On the ferromagnetism of AlFe2B2

Based on extensive Mossbauer effect (ME) and magnetization measurements, the orthorhombic AlFe₂B₂ was characterized as a ferromagnet (FM) because this character is evident as an onset of a FM transition at T_c=320 K and characteristic magnetizations isotherms below T_c. At liquid helium temperatures, the magnetization saturates to μ_sat≈1μ_B per Fe atom; a value which is half the one reported for the iron metal indicating a relatively more filled 3d band. The ME analysis revealed a hyperfine field H(0) of 88(2) kOe, an isomer shift (relative to Fe) of 0.50(2) mm/s, and a quadrupole parameter of 0.02 mm/s: all parameters extrapolated to zero Kelvin. The itinerant character of the magnetic moment will be discussed.     

Doping level and environment dependence of structural stability and magnetic properties in Mn-doped WS2 bilayer in first principles

We carried out first-principles electronic structure calculation to study the structural stability and magnetic properties of Mn-doped WS₂ ultra-thin films within the density functional theory. Adopting various configurations of Mn doping into WS₂ bilayer, we find that the magnetic phase can be manipulated among the ferromagnetic, antiferromagnetic, or ferrimagnetic phases by altering doping level and growth environment. Magnetic phase and strength are determined by magnetic coupling of Mn dopants 3d electrons which can be attributed crucially to the exchange interaction mediated by neighboring S atoms 3p electrons. Accompanying to the magnetic phase transition, the electronic structure reveals that transport properties switch from semiconducting with various bandgap to half-metallic states. This result implicates possible way to develop magnetic semiconductors based on Mn doped 2D WS₂ ultra-thin films for spintronics applications.     

Syntheses and characterization of the actinide manganese selenides ThMnSe3 and UMnSe3

The AnMnSe₃ (An=Th, U) compounds were synthesized from high-temperature solid-state reactions of the constituent elements at 1223 and 1273 K, respectively. Both compounds are isostructural with UFeS₃ and crystallize in the space group Cmcm of the orthorhombic system with four formula units in a cell. Cell constants (Å) at 153 K are: ThMnSe₃, 4.0304(4), 12.795(1), 9.2883(9); UMnSe₃, 3.931(5), 12.705(14), 9.148(10). The structure comprises layers of MnSe₆ octahedra that alternate with layers of AnSe₈ bicapped trigonal prisms along the b-axis. Because there are no Se-Se bonds in the structure of AnMnSe₃ the formal oxidation states of An/Mn/Se are 4+/2+/2−. UMnSe₃ is a ferromagnet with T_C=62 K.     

Magnetization modification by superconductivity in Nb/Ni80Fe20/Nb trilayers

We present experimental evidences for magnetization modification by superconductivity in a series of Nb/Ni₈₀Fe₂₀/Nb trilayers. By monitoring the magnetization in a zero field as a function of temperature, we observed an irreversibility in magnetization between the cooling and warming branches just above the superconducting transition temperature T_c. These results suggest that the magnetization of the ferromagnetic Ni₈₀Fe₂₀ layer is reduced by the mutual interactions between the ferromagnet and superconductor. Moreover, this effect diminishes with increasing thickness of the Ni₈₀Fe₂₀ layer, which indicates that the interaction between the superconducting and magnetic layers occurs mainly at the vicinity of the interfaces.     

Magnetic gap effect on the tunneling conductance in a topological insulator ferromagnet/superconductor junction

The tunneling conductance on the surface of a topological-insulator-based ferromagnet/superconductor (F/S) structure is studied where S is an s-wave superconductor with superconducting order parameter ∼Δ. The conductance is calculated based on the BTK formalism. The magnetization in F is applied along the z-direction () in order to induce the energy-mass gaps (m) for the Dirac electrons in the F-region. In this work, the influence of energy gap due to the magnetic field in the F-region on the conductance is emphasized. The Fermi energy mismatch between F (EFF=EF) and S (EFS=EF+U), where the gate potential U is applied to the electrode on top of S, is also considered. As a result, a biased voltage V can cause the conductance switch at eV=Δ, depending on the value of the magnetic field. The conductance is found to be linearly dependent on either m or U. The slope of the curve can also be adjusted. This linear behavior in a topological-insulator-based F/S structure may be valuable for electronic applications of the linear-control-current devices. The tunneling conductances of the quasi-Dirac-particle in a topological-insulator-based F/S junction are quite different from those of a graphene-based F/S junction.     

Effects of Rashba spin–orbit coupling interface on the orientation-dependent conductance in ferromagnet/spin-triplet superconductor junction

We study theoretically the tunneling charge conductance in ferromagnet/spin-triplet superconductor junction with the spin–orbit coupling interface. It is shown the symmetry of the conductance about the relative angle between the magnetization in ferromagnet and the d-vector in superconductor is broken due to the presence of the interfacial Rashba spin–orbit coupling. We present the conductance for various cases of the angle. For each angle, the spin-active mechanism provided by the interface is investigated. The interface effects for different spin polarization in the ferromagnet is also considered.