Spin transport in Ge/Si quantum dot array

摘要

We investigate theoretically the spin transport in array of Ge/Si quantum dots (QD). In frame of tight-binding approach we calculate the probability of hole spin flip for resonant tunneling through discrete energy levels in QD. Our studies are based on the calculation of overlap integrals between neighbouring quantum dots. For ground state the probability of tunneling with spin flip is two orders smaller than the probability of tunneling without spin flip. We find that the main source of spin flip is the structure-inversion asymmetry of Ge quantum dot. Every tunneling event is accompanied by the turning of spin on small angle and this provokes the spin flip. For excited states in QD, the probability of spin flip increases. We investigate the spin flip probability as dependent upon the size and the shape of a quantum dot.