ULTRASONIC ATTENUATION IN SUPERCONDUCTING AND NORMAL MERCURY

Abstract

Ultrasonic attenuation in superconducting and normal mercury has been studied with 20, 34, and 60 Mc/s longitudinal waves. The difference in attenuation between the superconducting and normal states below the transition temperature is greatly increased at the higher frequencies. The attenuation in the normal state is the same for both longitudinal and transverse critical magnetic fields and is independent of field strength between the critical value and 880 oersteds. The results disagree in some respects with those of MacKinnon and Myers. The experimental limitations of the method as a critical test of the Bardeen–Cooper–Schrieffer theory of superconductivity are discussed.