Pressure Dependence of the Superconducting Transition Temperature of dhcp and fcc Lanthanum

Abstract

The pressure dependence of the superconducting transition temperature of lanthanum has been extended from 10 to 40 kbar. The sample becomes predominantly fcc above 23 kbar. The superconducting transition temperature increases continuously up to 9°K, with a possible discontinuity at the phase change and a definite change of slope. The behavior in the fcc phase differs in sign with that predicted from thermal-expansion measurements at atmospheric pressure.