Magnetocaloric Effect in Two-Dimensional Diluted Ising Model: Appearance of Frustrations in the Ground State

TL;DR

This study investigates the magnetocaloric effect in a 2D diluted Ising model, revealing how impurity concentration and coupling strength induce frustrations and paramagnetic behavior at zero temperature.

Contribution

It demonstrates how nonmagnetic impurities and weak coupling lead to ground state frustrations and paramagnetism, providing a method to detect frustration via magnetic entropy variation.

Findings

Weak coupling and high impurity concentration cause ground state frustration.

Frustrations lead to paramagnetic response at zero temperature.

Magnetic entropy variation can indicate ground state frustration.

Abstract

The magnetocaloric effect in a two-dimensional Ising model is considered for different ratios between parameters of inter-site repulsion of nonmagnetic impurities and exchange coupling. Classical Monte Carlo simulations on a square lattice show that in case of weak coupling and at sufficiently high concentrations of nonmagnetic impurities the long-range ferromagnetic ordering breaks down to give isolated spin clusters in the ground state of the system. This leads to appearance of a paramagnetic response in the system at the zero temperature and nonzero entropy of the ground state. The feasibility to detect frustration of ground state using data on the magnetic entropy variation is discussed