Ring structures fabricated from HgTe/HgCdTe quantum wells have been used to study Aharonov-Bohm type conductance oscillations as a function of Rashba spin-orbit splitting strength. We observe non-monotonic phase changes indicating that an additional phase factor modifies the electron wave function. We associate these observations with the Aharonov-Casher effect. This is confirmed by comparison with numerical calculations of the magneto-conductance for a multichannel ring structure within the Landauer-B\"uttiker formalism.
@article{arxiv.cond-mat/0508396,
title = {Direct observation of the Aharonov-Casher phase},
author = {M. Koenig and A. Tschetschetkin and E. M. Hankiewicz and Jairo Sinova and V. Hock and V. Daumer and M. Schaefer and C. R. Becker and H. Buhmann and L. W. Molenkamp},
journal= {arXiv preprint arXiv:cond-mat/0508396},
year = {2009}
}