Anomalous temperature and field behaviors of magnetization in cubic lattice frustrated ferromagnets

TL;DR

This paper investigates the unusual temperature and magnetic field behaviors of magnetization in cubic frustrated ferromagnets, revealing fluctuation-induced stabilization and anomalous magnetization curves near the frustration point.

Contribution

It introduces a theoretical analysis using Dyson-Maleev formalism and Monte Carlo simulations to explain anomalous magnetization behaviors in frustrated ferromagnets.

Findings

Thermal fluctuations stabilize ferromagnetism near the frustration point.

Magnetization exhibits a concave temperature dependence matching experimental data.

Strong field dependence of magnetization observed near the frustration point.

Abstract

Thermodynamic properties of cubic Heisenberg ferromagnets with competing exchange interactions are considered near the frustration point where the coefficient $D$ in the spin-wave spectrum $E_{\mathbf{k}}\sim D k^{2}$ vanishes. Within the Dyson-Maleev formalism it is found that at low temperatures thermal fluctuations stabilize ferromagnetism by increasing the value of $D$. For not too strong frustration this leads to an unusual "concave" shape of the temperature dependence of magnetization, which is in agreement with experimental data on the europium chalcogenides. Anomalous temperature behavior of magnetization is confirmed by Monte Carlo simulation. Strong field dependence of magnetization (paraprocess) at finite temperature is found near the frustration point.