A quantitative study of the quantum interferometer in pure magnesium

Abstract

The quantum interferometer oscillations observed in the transverse magnetoresistance of Mg at liquid helium temperatures forJ∥[11\(\bar 1\)0] andH∥[1\(\bar 2\)00] have been experimentally investigated in detail. A new method of analyzing these quantum interference oscillations has been developed which permits direct line shape comparison between the experimentally observed magnetoresistance oscillations and theoretical calculations based on the stacked-mirror model of quantum transport. By using the stacked-mirror model in conjunction with the line shape comparison technique, virtually all of the approximations made in the initial studies of the quantum interferometer have been eliminated. Distinct and striking line shape changes in the magnetoresistance oscillations, critically dependent on the angle between the direction of the applied magnetic field and the basal plane of the Mg crystal, have also been observed and analyzed. This phenomenon provides direct evidence for the existence of long-range quantum phase coherence of the electron states in the Mg crystal over dimensions of ∼0.3 mm, corresponding to a quantum state lifetime τ of ∼3.5×10−10 sec. Experimental values for the three magnetic breakdown parameters that characterize the quantum interferometer in pure Mg areH1(kH=0)=3000±75 G,H2(kH=0)=10,000±1500 G, andH3(kH=0)=1000±250 G. Experimental evidence is also presented which shows a magnetic field dependence of the quantum state lifetime for some of the crystals studied.