Superconductivity in Indium Antimonide

Two samples of the metallic phase of indium antimonide were stabilized at atmospheric pressure by cooling semiconductor grade material from 100°C to 77°K at a pressure of 27 kbars, and then removing the pressure. Measurements of the magnetic moment of these samples down to 1.1°K were made using a sample-motion technique in a uniform magnetic field. Below 1.89°K, the samples exhibited bulk superconducting properties, in agreement with previous work. A high-field tail on the magnetization curves and the existence of considerable locked-in flux as the magnetic field was reduced were taken to be indications of a high state of residual strain in the sample. The slope of the critical field curve at 1.89°K was found to be ${\left(\frac{\partial H_c}{\partial T}\right)}_{\mathrm{Tc}}=-103\mathrm{}$G/°K. This is consistent with values found for soft superconductors with similar transition temperatures, and implies a normal state electronic specific heat per ${\mathrm{cm}}^3$, which is roughly half that of white tin. White tin has the same average ionic mass as metallic indium antimonide, and presumably the same electronic density.