Anisotropy of the Upper Critical Field of Superconducting Technetium

Abstract
The anisotropy of the upper critical field Hc2 of a noncubic superconductor was studied for the first time. A torque magnetometer was used to detect Hc2 between 2 and 7°K as a function of orientation in a small single crystal of technetium. The relative anisotropy of Hc2 consists of a large temperature-independent and possibly a small temperature-dependent part. The temperature-independent contribution can be attributed to the anisotropy of the effective mass.