The research on two-dimensional (2D) van der Waals (vdW) ferromagnets has promoted the development of ultrahigh-density and nanoscale data storage. However, intrinsic ferromagnetism in layered magnets is always subject to many factors, such as stacking orders, interlayer couplings, and the number of layers. Here, we report a magnetic transition from soft to hard ferromagnetic behaviors as the thickness of CrSiTe3 flakes decreases down to several nanometers. Phenomenally, in contrast to the negligible hysteresis loop in the bulk counterparts, atomically thin CrSiTe3 shows a rectangular loop with finite magnetization and coercivity as thickness decreases down to ~8 nm, indicative of a single-domain and out-of-plane ferromagnetic order. We find that the stray field is weakened with decreasing thickness, which suppresses the formation of the domain wall. In addition, thickness-dependent ferromagnetic properties also reveal a crossover from 3 dimensional to 2 dimensional Ising ferromagnets at a ~7 nm thickness of CrSiTe3, accompanied by a drop of the Curie temperature from 33 K for bulk to ~17 K for 4 nm sample.
@article{arxiv.2111.05495,
title = {Layer-controlled Ferromagnetism in Atomically Thin CrSiTe$_3$ Flakes},
author = {Cheng Zhang and Le Wang and Yue Gu and Xi Zhang and Liang-Long Huang and Ying Fu and Cai Liu and Junhao Lin and Xiaolong Zou and Huimin Su and Jia-Wei Mei and Jun-Feng Dai},
journal= {arXiv preprint arXiv:2111.05495},
year = {2021}
}