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.
Bibliographical noteFunding Information:
The authors would like to thank Sanghyun Lee, S. E. Dutton, Inho Hwang, and Y. Noda for their generous help and discussions. We would also like to acknowledge support from Jesus College of the University of Cambridge, IHT Kazatomprom, and the CHT Uzbekistan Programme. The work was carried out with financial support from the Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUST MISiS (No. K2-2017-024). The work of D.Kh. was supported by the German research Project No. SFB 1238 and by Köln University via the German Excellence Initiative. This work was supported by the van der Waals Materials Research Center NRF-2017R1A5A1014862 and the Institute for Basic Science of the Republic of Korea (Grant No. IBS-R009-G1).
© 2019 American Physical Society.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics