Critical properties of mixed spin-1 and spin-5/2 with equal and unequal crystal fields


CHINESE PHYSICS B, cilt.21, 2012 (SCI İndekslerine Giren Dergi) identifier identifier


The effects of assuming equal or unequal crystal fields (CF) on the phase diagrams of a mixed spin-1 and spin-5/2 system are investigated in terms of the recursion relations on the Bethe lattice (BL). The equal CF case was considered for the coordination numbers q = 3, 4, and 6, while for q = 3 the unequal CF case was also studied. It was found that for the equal CF case, the model exhibits second-order phase transitions and two compensation temperatures for all q, the reentrant behavior for q = 4 and first-order phase transitions and tricritical point (TCP) for q = 6. In the unequal CF case for q = 3, the system yields first-and second-order phase transitions, TCP's, and three compensation temperatures. In addition, the TCP's in a very short range are classified as the stable and unstable ones depending on their free energies.