Low temperature magnetic properties and spin structures of Ising Spin System with two-Spin and four-Spin interactions

Abstract

The magnetic properties of the spin S (=3/2 and 2) Ising systems with the bilinear exchange interaction J1SizSjz and the four-site four-spin interaction J4SizSjzSkzSlz are discussed by making use of the Monte Carlo (MC) simulation for the magnetization <Sz> and the magnetic specific heat CM and spin structures. The ferromagnetic spin arrangement ordered by the positive interaction J1 is destroyed and changed into lots of complicated spin structures with low energy by introducing negative four-spin interaction J4. Near the phase transitions of J4/J1 = -2/9 and -1/8 for S = 3/2 and 2, respectively, the thermal averages <Sz>, <SizSjzSkzSlz> and the specific heat CM show characteristic temperature dependences in the low temperature region. The change of spin structures of the system with the variation of the values of J1 and J4 are also investigated by using the result of the MC simulation and by the comparison of energies of the possible ground state spin structures.