Limited influence of diluted ferromagnetic dimers on Curie temperature in complex magnetic systems

TL;DR

This study examines how diluted ferromagnetic dimers influence the Curie temperature in complex magnetic systems, revealing their limited impact across various models and real materials.

Contribution

It provides a detailed analysis showing that diluted ferromagnetic dimers have limited influence on the Curie temperature in complex magnetic systems.

Findings

T_C remains finite even as I_A/I_B approaches infinity.

T_C changes are within +/-10% for 0 < I_A/I_B < infinity.

The influence of dimers is limited in complex magnetic materials.

Abstract

In this work we investigate Ising and classical Heisenberg models for two and three dimensional lattices in presence of diluted ferromagnetic dimers. For such models the Curie temperature as a function of ratio of intra-dimer exchange coupling constant I_A and other inter-site coupling constants I_B is calculated. In case dimer is treated exactly and environment within the mean-field approach it was found that even for I_A/I_B\to\infty T_C remains finite. Similar analysis is proposed for rhombohedral phase of intermetallic compound Gd2Fe17 where so-called Fe1-Fe1 "dumbbell" forms the diluted ferromagnetic dimer. It was shown that for such complex magnetic systems T_C is determined by all variety of exchange interactions and for the interval 0 < I_A/I_B < \infty T_C changes are not more than +/-10%.