The random-field specific heat critical behavior at high magnetic concentration:: Fe0.93Zn0.07F2

The specific heat critical behavior is measured and analyzed for a single crystal of the random-field Ising system Fe0.93Zn0.07F2 using pulsed heat and optical birefringence techniques. This high magnetic concentration sample does not exhibit the severe scattering hysteresis at low temperature seer; in lower concentration samples and its behavior is therefore that of an equilibrium random-field Ising model system. The equivalence of the behavior observed with pulsed heat techniques and optical birefringence is established. The critical peak appears to be a symmetric, logarithmic divergence, in disagreement with random-field model computer simulations. The random-field specific heat scaling function is determined. (C) 1998 Elsevier Science B.V. All rights reserved.