Low-temperature specific heat of Zr2(Co1-xNix) under magnetic fields

We measured the low-temperature specific heat in pseudo-binary alloyed compounds Zr-2(Co1-xNix) (0 less than or equal to x less than or equal to 0.3) in the temperature range from 1.5 to 8 K under various magnetic fields. In this system, T-c has one maximum ( approximate to 6 K) near x = 0.1. Corresponding to the maximum of T-c, the electronic specific heat coefficient gamma and energy gap 2 Delta(0)/k(B)T(c) are maximum near x = 0.1, that is, higher density of stares N(0) at the Fermi level near x = 0.1 results in higher T-c. Furthermore, the upper critical field, H-c2(0), is maximum near x = 0.1. (C) 2000 Elsevier Science B.V. All rights reserved.