Comment on "Experimental Demonstration of the Time Reversal Aharonov-Casher Effect"

TL;DR

This paper critiques a previous study by clarifying that the observed resistance oscillations are due to changes in carrier density, not spin-related effects, and highlights the misinterpretation of the Aharonov-Casher effect.

Contribution

It corrects the interpretation of resistance oscillations in semiconductor rings, emphasizing the role of carrier density changes over spin effects.

Findings

Oscillations are caused by carrier density changes, not spin effects.

Strong spin relaxation destroys spin-related oscillations.

Misinterpretation of AAS as Aharonov-Casher effect in prior work.

Abstract

In a recent Letter, Bergsten and co-authors have studied the resistance oscillations with gate voltage and magnetic field in arrays of semiconductor rings and interpreted the oscillatory magnetic field dependence as Altshuler-Aronov-Spivak (AAS) oscillations and oscillatory dependence on gate voltage as the Aharonov-Casher (AC) effect. This Comment shows that Bergsten and co-authors incorrectly identified AAS effect as a source of resistance oscillations in magnetic field, that spin relaxation in their experimental setting is strong enough to destroy oscillatory effects of spin origin, and that the oscillations are caused by changes in carrier density and the Fermi energy by gate, and are unrelated to spin.