Aharonov–Bohm rings with strong spin–orbit interaction: the role of sample-specific properties

We present low-temperature transport experiments on Aharonov–Bohm (AB) rings fabricated from two-dimensional hole gases in p-type GaAs/AlGaAs heterostructures. Highly visible h/e (up to 15%) and h/2e oscillations, present for different gate voltages, prove the high quality of the fabricated devices. Like in previous work, a clear beating pattern of the h/e and h/2e oscillations is present in the magnetoresistance, producing split peaks in the Fourier spectrum. The magnetoresistance evolution is presented and discussed as a function of temperature and gate voltage. It is found that sample specific properties have a pronounced influence on the observed behaviour. For example, the interference of different transverse modes or the interplay between h/e oscillations and conductance fluctuations can produce the features mentioned above. In previous work they have occasionally been interpreted as signatures of spin–orbit interaction (SOI)-induced effects. In the light of these results, the unambiguous identification of SOI-induced phase effects in AB rings remains still an open and challenging experimental task. (paper)