Spin-Hall effect in semiconductor heterostructures with cubic Rashba spin-orbit interaction

We study the spin-Hall effect in systems with weak cubic Rashba spin-orbit interaction. To this end we derive particle and spin diffusion equations and explicit expressions for the spin-current tensor in the diffusive regime. We discuss the impact of electric fields on the Green's functions and the diffusion equations and establish a relationship between the spin-current tensor and the spin diffusion equations for the model under scrutiny. We use our results to calculate the edge spin-accumulation in a spin-Hall experiment and show that there is also a new Hall-like contribution to the electric current in such systems.Comment: 14 page

Spin Transport in Disordered Two-Dimensional Hopping Systems with Rashba Spin-Orbit Interaction

The influence of Rashba spin-orbit interaction on the spin dynamics of a topologically disordered hopping system is studied in this paper. This is a significant generalization of a previous investigation, where an ordered (polaronic) hopping system has been considered instead. It is found, that in the limit, where the Rashba length is large compared to the typical hopping length, the spin dynamics of a disordered system can still be described by the expressions derived for an ordered system, under the provision that one takes into account the frequency dependence of the diffusion constant and the mobility (which are determined by charge transport and are independent of spin). With these results we are able to make explicit the influence of disorder on spin related quantities as, e.g., the spin life-time in hopping systems.Comment: 12 pages, 6 figures, some clarifications adde

Excitation of spin waves on a cylindrical semiconductor heterostructure with Rashba spin-orbit interaction

Elementary excitations in a paramagnetic semiconductor quantum well confined to a cylindrical surface are theoretically studied on the basis of coupled spin-charge drift-diffusion equations. The electric-field-mediated eigenmodes are optically excited by an oscillating interference pattern, which induces a current in the outer circuit. For a cylinder with a given radius, sharp resonances are predicted to occur in the steady-state current response, which are due to weakly damped spin remagnetization waves.Comment: 7 pages, 1figur

Spin Transport in Two Dimensional Hopping Systems

A two dimensional hopping system with Rashba spin-orbit interaction is considered. Our main interest is concerned with the evolution of the spin degree of freedom of the electrons. We derive the rate equations governing the evolution of the charge density and spin polarization of this system in the Markovian limit in one-particle approximation. If only two-site hopping events are taken into account, the evolution of the charge density and of the spin polarization is found to be decoupled. A critical electric field is found, above which oscillations are superimposed on the temporal decay of the total polarization. A coupling between charge density and spin polarization occurs on the level of three-site hopping events. The coupling terms are identified as the anomalous Hall effect and the recently proposed spin Hall effect. Thus, an unpolarized charge current through a sheet of finite width leads to a transversal spin accumulation in our model system.Comment: 15 pages, 3 figure

Novel experimental setup for megahertz X-ray diffraction in a diamond anvil cell at the High Energy Density (HED) instrument of the European X-ray Free-Electron Laser (EuXFEL)

The high-precision X-ray diffraction setup for work with diamond anvil cells (DACs) in interaction chamber 2 (IC2) of the High Energy Density instrument of the European X-ray Free-Electron Laser is described. This includes beamline optics, sample positioning and detector systems located in the multipurpose vacuum chamber. Concepts for pump-probe X-ray diffraction experiments in the DAC are described and their implementation demonstrated during the First User Community Assisted Commissioning experiment. X-ray heating and diffraction of Bi under pressure, obtained using 20 fs X-ray pulses at 17.8 keV and 2.2 MHz repetition, is illustrated through splitting of diffraction peaks, and interpreted employing finite element modeling of the sample chamber in the DAC