Regensburg 2002 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 2: Transporteigenschaften
HL 2.2: Vortrag
Montag, 11. März 2002, 10:45–11:00, H13
Persistent Non-ergodic Fluctuations in the insulating the regime with and without spin-orbit coupling. — •Rangel Rafael1, Hans J. Herman1, and Ernesto Medina2 — 1ICA1, Univ. Stuttgart, Pfaffenwaldring 27, 70569 Stuttgart, Germany9 Stuttgart — 2Centro de Fisica, IVIC, Caracas, Venezuela
We give a unified picture of the mesoscopic conductance fluctuations in the deep insulating regime (DIR) within the Nguyen, Spivak and Shklovskii model with and without spin-orbit coupling (SOC). Without SOC, we find that fluctuations of the log-conductance are persistent above a saturation field, where one has approximately stationary random process whereas in the SOC case the saturation field is negligible and stationary is very well realized. A rather weak decaying behavior of the correlation function, even weaker in the case of SOC is found, such that Slutski’s theorem can be invoked to conclude that the whole stochastic process defined by the log-conductance is non-ergodic in both cases. As a consequence the commonly used criterion to test the ergodicity of fluctuations, namely, that the disorder average of the variance in the field compares with the field average of the variance over disorder fails. Using the replica approach, we derive the weak localization analogs of the ‘cooperon’ and ‘diffuson’ which permits us to analyze the decaying behavior of the correlation function. Our predictions explains well experiments in the DIR.