THE SPECIFIC-HEAT AT REENTRANCES - IS THERE A BREAK IN ITS UNIVERSAL BEHAVIOR

Abstract

Using the procedure previously obtained by the authors, we obtain the specific heat of the two-dimensional generalized Ising model when reentrancy occurs. For the case of single reentrancy and when the two transition temperatures are similar (single degeneracy), then the specific heat behaves as DELTA2 ln Absolute value of DELTA. For the case of double reentrancy one has two possibilities: (i) Single degeneracy. The behavior of the specific heat is again DELTA2 ln Absolute value of DELTA. (ii) Double degeneracy. The behavior is now DELTA4 ln Absolute value of DELTA. When higher reentrancies occur there is the possibility of higher degeneracy in the values of the transition temperatures, in which case the specific heat behaves as DELTA(k) ln Absolute value of DELTA with k > 4. These results are obtained in general, i.e. independently of the details of the interactions between spins of the system. Therefore, we conclude that there is a breakdown in the universal behavior of the specific heat.