Specific heat measurements on the site-diluted dipolar ising ferromagnet LiTbpY1− pF4

Abstract

Specific heat measurements on the diluted dipolar ferromagnet LiTb p Y 1− p F 4 are presented for 0.2⩽ p⩽1.0. The measured critical temperatures T c( p) agree with those obtained from previous susceptibility and magnetization measurement. The shape of the specific heat curve is found to be largely influenced by the singlet-singlet separation in the ground state pseudo-doublet, which may explain why below p ≈ 0.325 a λ-anomaly in the specific heat curve can no longer be discerned. For a sample with p = 0.20 we find no evidence of an enhanced nuclear spin ordering, as was suggested by Folkins et al.