Quantum-Classical Phase Transition of the Escape Rate of Two-Sublattice Antiferromagnetic Large Spins
Abstract
The Hamiltonian of a two-sublattice antiferromagnetic spins, with single (hard-axis) and double ion anisotropies described by H = J {\hat S}1...\hatS 2-2Jz \hat {S}1z\hat {S}2z+K(\hat {S}1z2 +\hat {S}2z2) is investigated using the method of effective potential. The problem is mapped to a single particle quantum-mechanical Hamiltonian in terms of the relative coordinate and reduced mass. We study the quantum-classical phase transition of the escape rate of this model. We show that the first-order phase transition for this model sets in at the critical value Jc = (Kc+Jz, c)/2 while for the anisotropic Heisenberg coupling H = J(S1xS2x +S1yS2y) + JzS1zS2z + K(S1z2+ S2z2) we obtain Jc = (2Kc-Jz, c)/3. The phase diagrams of the transition are also studied.
- Publication:
-
International Journal of Modern Physics B
- Pub Date:
- November 2014
- DOI:
- 10.1142/S0217979214500088
- Bibcode:
- 2014IJMPB..2850008O
- Keywords:
-
- Phase transition;
- tunneling;
- effective potential;
- 75.45.+j;
- 75.10.Jm;
- 75.30.Gw;
- 03.65.Sq;
- Macroscopic quantum phenomena in magnetic systems;
- Quantized spin models;
- Magnetic anisotropy;
- Semiclassical theories and applications