Spin convertance at magnetic interfaces Zhang, Steven S.-L.; Zhang, Shufeng
Physical review. B, Condensed matter and materials physics,
12/2012, Letnik:
86, Številka:
21
Journal Article
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Odprti dostop
Exchange interaction between conduction electrons and magnetic moments at magnetic interfaces leads to mutual conversion between spin current and magnon current. We introduce a concept of spin ...convertance which quantitatively measures magnon current induced by spin accumulation and spin current created by magnon accumulation at a magnetic interface. We predict several phenomena on charge and spin drag across a magnetic insulator spacer for a few layered structures.
In a semiconductor heterostructure, the Coulomb interaction is responsible for the electric current drag between two 2D electron gases across an electron impenetrable insulator. For two metallic ...layers separated by a ferromagnetic insulator (FI) layer, the electric current drag can be mediated by a nonequilibrium magnon current of the FI. We determine the drag current by using the semiclassical Boltzmann approach with proper boundary conditions of electrons and magnons at the metal-FI interface.
Surface states of three-dimensional topological insulators exhibit the phenomenon of spin–momentum locking, whereby the orientation of an electron spin is determined by its momentum. Probing the spin ...texture of these states is of critical importance for the realization of topological insulator devices, but the main technique currently available is spin- and angle-resolved photoemission spectroscopy. Here we reveal a close link between the spin texture and a new kind of magnetoresistance, which depends on the relative orientation of the current with respect to the magnetic field as well as the crystallographic axes, and scales linearly with both the applied electric and magnetic fields. This bilinear magnetoelectric resistance can be used to map the spin texture of topological surface states by simple transport measurements. For a prototypical Bi2Se3 single layer, we can map both the in-plane and out-of-plane components of the spin texture (the latter arising from hexagonal warping). Theoretical calculations suggest that the bilinear magnetoelectric resistance originates from conversion of a non-equilibrium spin current into a charge current under application of the external magnetic field.
An intriguing property of a three-dimensional (3D) topological insulator (TI) is the existence of surface states with spin-momentum locking, which offers a new frontier of exploration in spintronics. ...Here, we report the observation of a new type of Hall effect in a 3D TI Bi_{2}Se_{3} film. The Hall resistance scales linearly with both the applied electric and magnetic fields and exhibits a π/2 angle offset with respect to its longitudinal counterpart, in contrast to the usual angle offset of π/4 between the linear planar Hall effect and the anisotropic magnetoresistance. This novel nonlinear planar Hall effect originates from the conversion of a nonlinear transverse spin current to a charge current due to the concerted actions of spin-momentum locking and time-reversal symmetry breaking, which also exists in a wide class of noncentrosymmetric materials with a large span of magnitude. It provides a new way to characterize and utilize the nonlinear spin-to-charge conversion in a variety of topological quantum materials.
Tailoring Gilbert damping of metallic ferromagnetic thin films is one of the central interests in spintronics applications. Here we report a giant Gilbert damping anisotropy in epitaxial ...Co_{50}Fe_{50} thin films with a maximum-minimum damping ratio of 400%, determined by broadband spin-torque ferromagnetic resonance as well as inductive ferromagnetic resonance. We conclude that the origin of this damping anisotropy is the variation of the spin orbit coupling for different magnetization orientations in the cubic lattice, which is further corroborated from the magnitude of the anisotropic magnetoresistance in Co_{50}Fe_{50}.
Behind the Mask: Was I Really That Bad? Zhang, Steven E
Clinical orthopaedics and related research,
2024-Apr-01, 2024-04-00, 20240401, Letnik:
482, Številka:
4
Journal Article
Wave energy is one of the most available energy sources in oceans. In this work, a design of high power density triboelectric nanogenerator (TENG) based on a tower structure is proposed for ...harvesting wave energy from arbitrary directions. Such tower-like TENG (T-TENG) consists of multiple units made of polytetrafluoroethylene balls and three-dimensional printed arc surface coated with melt adhesive reticulation nylon film. The power generation model coupled with the kinetic model for the T-TENG is proposed and discussed. The T-TENG can effectively convert arbitrary directional wave energy into electrical energy by utilizing charged balls rolling on an optimized arc surface due to ocean wave excitation. In addition, it is found that the power density of the present T-TENG increases linearly from 1.03 W/m3 to 10.6 W/m3 by increasing the units from 1 to 10 in one block. This supports that the power density of the T-TENG increases proportionally with the number of units connected in parallel without rectifiers due to its distinctive mechanism and structure. Therefore, the design of T-TENG provides an innovative and effective approach toward large-scale blue energy harvesting by connecting more blocks to form T-TENG networks.
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