We present comprehensive measurements of the structural, magnetic and electronic properties of layered van-der-Waals ferromagnet VI3 down to low temperatures. Despite belonging to a well studied family of transition metal trihalides, this material has received very little attention. We outline, from high-resolution powder x-ray diffraction measurements, a corrected room-temperature crystal structure to that previously proposed and uncover a structural transition at 79 K, also seen in the heat capacity. Magnetization measurements confirm VI3 to be a hard ferromagnet (9.1 kOe coercive field at 2 K) with a high degree of anisotropy, and the pressure dependence of the magnetic properties provide evidence for the two-dimensional nature of the magnetic order. Optical and electrical transport measurements show this material to be an insulator with an optical band gap of 0.67 eV - the previous theoretical predictions of d-band metallicity then lead us to believe VI3 to be a correlated Mott insulator. Our latest band structure calculations support this picture and show good agreement with the experimental data. We suggest VI3 to host great potential in the thriving field of low-dimensional magnetism and functional materials, together with opportunities to study and make use of low-dimensional Mott physics.
@article{arxiv.1812.05284,
title = {Bulk properties of van-der-Waals hard ferromagnet VI3},
author = {Suhan Son and Matthew J. Coak and Nahyun Lee and Jonghyeon Kim and Tae Yun Kim and Hayrullo Hamidov and Hwanbeom Cho and Cheng Liu and David M. Jarvis and Philip A. C. Brown and Jae Hoon Kim and Cheol-Hwan Park and Daniel I. Khomskii and Siddharth S. Saxena and Je-Geun Park},
journal= {arXiv preprint arXiv:1812.05284},
year = {2019}
}