Unitarity of scattering and edge spin accumulation

Surface roughness scattering in multisubband accumulation layers

Accumulation layers with very large concentrations of electrons where many subbands are filled became recently available due to ionic liquid and other new methods of gating. The low temperature mobility in such layers is limited by the surface roughness scattering. However theories of roughness scattering so far dealt only with the small-density single subband two-dimensional electron gas (2DEG). Here we develop a theory of roughness-scattering limited mobility for the multisubband large concentration case. We show that with growing 2D electron concentration $n$ the surface dimensionless condu…

非厄米特系统中的双端散射与广义单位性

Biorthogonal scattering and generalized unitarity in non-Hermitian systems

研究非厄米特双极系统中双端散射的非互易性和广义单位性，揭示双正交性对恢复单位性的作用及增强传输的物理机制。

Surveying the Multicomponent Scattering Matrix: Unitarity and Symmetries

Multicomponent-multiband fluxes of spim-charge carriers, whose components propagate mixed and synchronously, with \emph{a priori} nonzero incoming amplitudes, do not obey the standard unitarity condition on the scattering matrix for an arbitrary basis set. For such cases, we have derived a robust theoretical procedure, which is fundamental in quantum-transport problems for unitarity preservation and we have named after \emph{structured unitarity condition}. Our approach deals with $(N \times N)$ interacting components (for $N \geq 2$), within the envelope function approximation (EFA), and yet …

Spin accumulation in the semi classical and quantum regimes

We consider spin accumulation at a ferromagnet--normal metal interface in the presence of magnetic scattering in the normal metal. In the classical regime, we discuss the inverse Drude scaling of the conductance as a function of the interface transparencies. We present a treatment based on an exact solution of the Boltzmann equation. In the quantum regime, we solve a single impurity ``spin-flip Fabry Perot interferometer'' for quantum coherent multiple scatterings, in which we find a resonance in the spin flip channels. This resonance appears to be the quantum analog of the semi classical inve…

Edge spin accumulation in a ballistic regime

We consider a mesoscopic {\it ballistic} structure with Rashba spin-orbit splitting of the electron spectrum. The ballistic region is attached to the leads with a voltage applied between them. We calculate the edge spin density which appears in the presence of a charge current through the structure due to the difference in populations of electrons coming from different leads. Combined effect of the boundary scattering and spin precession leads to oscillations of the edge polarization with the envelope function decaying as a power law of the distance from the boundary. The problem is solved wit…

Accumulation of magnetoelastic bosons in yttrium iron garnet: kinetic theory and wave vector resolved Brillouin light scattering

We derive and solve quantum kinetic equations describing the accumulation of magnetoelastic bosons in an overpopulated magnon gas realized in a thin film of the magnetic insulator yttrium iron garnet. We show that in the presence of a magnon condensate, there is a non-equilibrium steady state in which incoherent magnetoelastic bosons accumulate in a narrow region in momentum space for energies slightly below the bottom of the magnon spectrum. The results of our calculations agree quite well with Brillouin light scattering measurements of the stationary non-equilibrium state of magnons and magn…