Geometric spin phases in Aharonov-Casher interference

Abstract

We review theoretical and experimental results on geometric spin-phase detection and manipulation in mesoscopic Rashba spin-orbit (SO) rings. A one-dimensional (1D) model capable of providing physical insight into electronic spin dynamics and interferometry under SO and Zeeman fields is developed to discuss spin transport in Rashba rings. The model gives an accurate prediction of the Aharonov-Casher (AC) oscillation period in the conductance of Rashba rings that eventually leads to the identification of geometric spin-phase components in experiments. Thus, we experimentally demonstrate the radius dependence of the geometric spin phases in AC interference. In addition, we find a universal oscillatory behavior of the AC effect, corresponding to the observation of an effective spin-dependent flux similar to the Aharonov-Bohm (AB) flux. The experimental results show geometric phases away from the adiabatic limit. Moreover, phase shifts in the AC oscillations induced by an in-plane magnetic field are consistent with the geometric spin phases predicted by the theory, demonstrating that geometric spin phases can be controlled independently from dynamical spin phases by field engineering.