We investigated the evolution of ferromagnetism in layered Fe3GeTe2 flakes under different pressures and temperatures using in situ magnetic circular dichroism (MCD) spectroscopy. We found that the rectangle shape of hysteretic loop under an out-of-plane magnetic field sweep can sustain below 7 GPa. Above that pressure, an intermediate state appears at low temperature region signaled by an 8-shaped skew hysteretic loop. Meanwhile, the coercive field and Curie temperature decrease with increasing pressures, implying the decrease of the exchange interaction and the magneto-crystalline anisotropy under pressures. The intermediate phase has a labyrinthine domain structure, which is attributed to the increase of ratio of exchange interaction to magneto-crystalline anisotropy based on Jagla's theory. Moreover, our calculation results reveal a weak structural transition around 6 GPa, which leads to a drop of the magnetic momentum of Fe ions.
@article{arxiv.2005.03195,
title = {Pressure-dependent Intermediate Magnetic Phase in Thin Fe$_3$GeTe$_2$ Flakes},
author = {Heshen Wang and Runzhang Xu and Cai Liu and Le Wang and Zhan Zhang and Huimin Su and Shanmin Wang and Yusheng Zhao and Zhaojun Liu and Dapeng Yu and Jia-Wei Mei and Xiaolong Zou and Jun-Feng Dai},
journal= {arXiv preprint arXiv:2005.03195},
year = {2020}
}