Dresden 2006 – scientific programme

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HL: Halbleiterphysik

HL 29: Transport properties II

HL 29.2: Talk

Wednesday, March 29, 2006, 17:15–17:30, HSZ 01

Direct observation of the Aharonov-Casher phase — •Markus König, Anna Tschetschetkin, Volkmar Hock, Matthias Schäfer, Charles R. Becker, Hartmut Buhmann, and Laurens W. Molenkamp — Physikalisches Institut (EP 3), Universität Würzburg, Am Hubland, 97074 Würzburg, Germany

Since its prediction in the 1980s, the concept of geometric phases has aroused much interest. One special case of a geometric phase is the Aharonov-Casher (AC) phase [1], which is acquired by a particle with a magnetic moment, which moves around an electric field. Nitta et al. [2] stated that the existence of the AC phase affects the transmission probability in ring shaped devices with spin-orbit coupling.

Apart from the Aharonov-Bohm (AB) effect, there has been no direct observation of any other phase related effects in a solid state system. So far, only some additional structures in the Fourier transform have been interpreted as indirect evidence of the geometric phase.

We present experimental results obtained on HgTe quantum well based ring structures, which have been used to study AB type conductance oscillations as a function of Rashba spin-orbit splitting energy. Non-monotonic phase changes were observed, indicating that an additional phase factor modifies the electron wave function. We associate these observations with the Aharonov-Casher effect. This interpretation is confirmed by numerical calculations.

[1] Y. Aharonov and A. Casher, Phys. Rev. Lett. 53, 319 (1984). [2] J. Nitta, F. E. Meijer, and H. Takayanagi, Appl. Phys. Lett. 75, 695 (1999).