Upper critical field of Ti and alpha-TiAl alloys: Evidence of an intrinsic type-II superconductivity in pure Ti

Abstract

The upper critical field H-c2 of alpha-Ti1-xAlx(0 less than or equal to x less than or equal to 0.1) alloys has been investigated in detail. The behaviors can well be described by the theory of type-II superconductors. The electronic specific heat deduced from the superconducting properties is in excellent agreement with previous calorimetric measurements. However, the Fermi velocity obtained here is substantially lower than predicted by band calculation. The present work gives clear evidence that pure Ti is an intrinsic type-II superconducting element due to its very low renormalized Fermi velocity.