ENSEMBLE-AVERAGE SPECTRUM OF AHARONOV-BOHM CONDUCTANCE OSCILLATIONS -EVIDENCE FOR SPIN-ORBIT-INDUCED BERRYS PHASE

We have experimentally investigated Aharonov-Bohm conductance oscillat ions in two-dimensional tings in the presence of a strong Rashba spin- orbit interaction. The peak of the ensemble average spectrum correspon ding to the h/e oscillations is split in several samples. We argue tha t the splitting originates from the geometric phase acquired by an ele ctron spin under the influence of the spinorbit interaction. Our resul ts demonstrate how the ensemble average spectrum provides information otherwise not easily accessible.