Journal of Statistical Mechanics Theory and Experiment
Single-point ground states and residual entropies in the antiferromagnetic Ising model with multisite interaction on the tetrahedral chain: exact results
E. Jurčišinová, Marian Jurčisin
Abstract
Abstract. The antiferromagnetic spin-1/2 Ising model with the presence of the multisite interaction and in the external magnetic field on the infinite tetrahedral chain is solved exactly by using the transfer matrix method. Using the exact expression for the free energy per site of the model the thermodynamic properties of the model are investigated in detail. It is shown that the total magnetisation per site forms the magnetisation plateaus at low temperatures, the properties of which depend on the strength of the multisite interaction. The set of all possible ground states is found and discussed. The existence of the so-called single-point ground states is shown and their properties are studied in detail. The entropy per site of the model is investigated and the exact expressions for the residual entropies of all ground states are found and their macroscopic degeneracies are discussed. The existence of the ground states with the same value of magnetisation but with different entropies is observed. In addition, the behaviour of the susceptibility and the specific heat is also studied.