Physics of Fe3GaTe2 having higher Curie temperature (TC) than Fe3GeTe2 is explored theoretically in the framework of magnetic exchange interactions. Fe3GaTe2 and Fe3GeTe2 are isostructural, with Fe3GaTe2 having one less valence electron and smaller nearest-neighbor exchange coefficients (J1 and J2), challenging the conventional notion that larger J1 or J2 leads to a higher TC. We show that higher order exchange coefficients, J3 or higher, of Fe3GaTe2 are positive whereas those of Fe3GeTe2 are negative. As a consequence, total sum of all possible exchange coefficients in Fe3GaTe2 are larger than Fe3GeTe2, which accounts for higher TC. To validate these findings, TC are computed using both mean-field theory and Monte Carlo simulation. Indeed, higher-order exchange interactions, when properly accounting for the number of neighbors, confirm the higher TC of Fe3GaTe2.
Cite
@article{arxiv.2504.17998,
title = {Why Fe$_3$GaTe$_2$ has higher Curie temperature than Fe$_3$GeTe$_2$?},
author = {Bomin Kim and Tumentsereg Ochirkhuyag and Dorj Odkhuu and S. H. Rhim},
journal= {arXiv preprint arXiv:2504.17998},
year = {2025}
}