Z.Y. Li

Mean-field renormalization-group study of surface magnetism

Abstract Surface effects on critical behavior in a semi-infinite Ising ferromagnet with a free surface, the random field or amorphization at the surface only, are investigated by the use of the mean-field renormalization-group method.

Critical behavior in the amorphous ising ferromagnet with a random field

Abstract Within the differential operator method and the effective-field approximation, the critical behaviour of the amorphous Ising ferromagnet with a random field is studied. Tricritical points and reentrant phenomena are discussed. The influence of the random field and the amorphization on the transition temperature is also investigated.

Thermodynamic properties of the site-bond diluted Ising ferromagnet on an anisotropic square lattice

Abstract Within the framework of an effective-field theory, we calculate the magnetization, specific heat and susceptibility of a quenched site-bond diluted Ising ferromagnet on a square lattice with both anisotropic coupling constants and anisotropic bond occupancy probabilities. It is shown that these thermodynamic quantities exhibit some interesting behavior as a function of temperature for selected concentrations of magnetic atoms and anisotropic bonds with anisotropic coupling constants.

Surface phase transition and tricritical point of a semi-infinite Ising ferromagnet with a surface trimodal random field

Abstract Within the mean-field renormalization group scheme, the critical behavior of a uniform and of an amorphous surface with a trimodal surface random-field distribution in a semi-infinite Ising ferromagnet are investigated. Some interesting results are obtained.

The site-bond diluted ferromagnetic system in the potts model

Abstract Within an effective field theory framework which has been used for Ising model, through the generalization of Callen identities, the thermodynamic properties of the site-bond diluted ferromagnetic system in the q -state Potts model are investigated.

Instability in the quantum Sherrington-Kirkpatrick Ising spin glass with a transverse and a trimodal random longitudinal field☆

Abstract The infinite-range Sherrington-Kirkpatrick Ising spin-glass model with a transverse field and a random longitudinal field is studied by combining the pair approximation with the discretized path-integral representation. The effects of a transverse field and a random longitudinal field on the instability freezing boundary are examined when random fields are trimodal, and the previous results for the vanishing of the longitudinal field can be recovered.

Magnetic properties of a random mixture system with anisotropic Heisenberg exchange on the Bethe lattice

Abstract The paper is an investigation of the magnetic susceptibilities of a random binary Bethe lattice with anisotropic Heisenberg exchange at high temperature by the adoption of the extended technique of the pair approximation.