Frustration Effects in Antiferromagnetic FCC Heisenberg Films

TL;DR

This paper investigates frustration effects in antiferromagnetic FCC Heisenberg films, revealing surface-induced ground state degeneracy reduction, phase coexistence, reentrant phases, and quantum fluctuation impacts through Monte Carlo and Green's function methods.

Contribution

It combines Monte Carlo simulations and Green's function analysis to explore surface effects, phase transitions, and quantum fluctuations in frustrated antiferromagnetic films.

Findings

Surface reduces bulk ground state degeneracy.

Critical surface interaction leads to coexisting orderings.

Quantum fluctuations influence low-temperature behavior.

Abstract

We study the effects of frustration in an antiferromagnetic film of FCC lattice with Heisenberg spin model including an Ising-like anisotropy. Monte Carlo (MC) simulations have been used to study thermodynamic properties of the film. We show that the presence of the surface reduces the ground state (GS) degeneracy found in the bulk. The GS is shown to depend on the surface in-plane interaction $J_s$ with a critical value at which ordering of type I coexists with ordering of type II. Near this value a reentrant phase is found. Various physical quantities such as layer magnetizations and layer susceptibilities are shown and discussed. The nature of the phase transition is also studied by histogram technique. We have also used the Green's function (GF) method for the quantum counterpart model. The results at low-$T$ show interesting effects of quantum fluctuations. Results obtained by the GF method at high $T$ are compared to those of MC simulations. A good agreement is observed.