Frustrated mixed spin1/2 and spin1 Ising ferrimagnets on a triangular lattice
Abstract
Mixed spin1/2 and spin1 Ising ferrimagnets on a triangular lattice with sublattices A, B, and C are studied for two spinvalue distributions (S_{A},S_{B},S_{C}) =(1 /2 ,1 /2 ,1 ) and (1 /2 ,1 ,1 ) by Monte Carlo simulations. The nonbipartite character of the lattice induces geometrical frustration in both systems, which leads to the critical behavior rather different from their ferromagnetic counterparts. We confirm secondorder phase transitions belonging to the standard Ising universality class occurring at higher temperatures, however, in both models these change at tricritical points (TCP) to firstorder transitions at lower temperatures. In the model (1 /2 ,1 /2 ,1 ) , TCP occurs on the boundary between paramagnetic and ferrimagnetic (±1 /2 ,±1 /2 ,∓1 ) phases. The boundary between two ferrimagnetic phases (±1 /2 ,±1 /2 ,∓1 ) and (±1 /2 ,∓1 /2 ,0 ) at lower temperatures is always first order and it is joined by a line of secondorder phase transitions between the paramagnetic and the ferrimagnetic (±1 /2 ,∓1 /2 ,0 ) phases at a critical endpoint. The tricritical behavior is also confirmed in the model (1 /2 ,1 ,1 ) on the boundary between the paramagnetic and ferrimagnetic (0 ,±1 ,∓1 ) phases.
 Publication:

Physical Review E
 Pub Date:
 May 2015
 DOI:
 10.1103/PhysRevE.91.052138
 arXiv:
 arXiv:1503.00589
 Bibcode:
 2015PhRvE..91e2138Z
 Keywords:

 05.50.+q;
 64.60.De;
 75.10.Hk;
 75.30.Kz;
 Lattice theory and statistics;
 Statistical mechanics of model systems;
 Classical spin models;
 Magnetic phase boundaries;
 Condensed Matter  Statistical Mechanics
 EPrint:
 23 pages, 12 figures