Gantmakher-Kaner oscillations at 79 GHz in single-crystal copper plates

Abstract

Thin plates of high-purity, single-crystal copper have been investigated with the microwave transmission technique at 79 GHz with the utilization of a magnetic field perpendicular to the sample surfaces and parallel to the $〈100〉$, $〈110〉$, and $〈111〉$ crystal axes. The observed Gantmakher-Kaner oscillations are compared with a theoretical model first proposed by Phillips, Baraff, and Schmidt to explain their data in copper at 35 GHz for a $〈100〉$ orientation. With the aid of their model we find two classes of signals: (a) those arising from a sharp cutoff of the topological effectiveness, and (b) those due to an extremal helical trajectory. The generally excellent agreement between observation and the predictions of the model for all three crystal orientations confirms the physical significance of the model, although it is lacking a rigorous mathematical derivation.