Specific-heat measurements of HoxY

Abstract

We report on specific-heat measurements of (Ho/sub x/Y/sub 1/..sqrt../sub x/)Co/sub 2/ in the temperature range from 1.5 to 60 K. Sharp peaks at the Curie temperature T/sub C/ and the spin-reorientation temperature T/sub r/ characterize the temperature dependence for 0.5less than or equal toxless than or equal to1. For 0.2less than or equal toxless than or equal to0.4 the magnetic specific heat C/sub m/ indicates spin-glass-like behavior, which appears to be in agreement with freezing phenomena observed in magnetic measurements. From the analysis of the magnetic entropy S/sub m/, we deduce that the induced Co moment can be referred to as itinerant in the sense of the Stoner theory. In the dilute Ho-concentration range, various anomalies are observed as, e.g., an enhancement of the effective electronic specific heat ..gamma.. and the effective Debye temperature FTHETA/sub D/ (of about 400% and 100%, respectively) and significant upturns of the C/sub p/T versus T/sup 2/ graphs together with a pronounced reduction of the magnetic entropy. These anomalies are discussed in terms of spin fluctuations;the loss of the magnetic entropy for x<0.2 may point to an instability of the Ho moment