at ambient and finite pressures*

Magnetic van-der-Waals (vdW) materials are considered as promising candidate systems to realize low-dimensional ferromagnetism in semiconductors. Here, we present a thermodynamic (specific heat and magnetization) and microscopic NMR study on bulk single crystals of the recently discovered ferromagnetic vdW material VI₃ at ambient and finite pressures [1]. Our results show that VI₃ undergoes a structural transition, which is subsequently followed by two ferromagnetic transitions at ambient pressure, giving rise to two distinct magnetically-ordered V sites for low temperatures. Upon increasing pressure, the two magnetic transitions merge at p ~ 0.6 GPa, and for even higher pressures (p ~ 1.25 GPa) merge with the structural transition. From these observations, we infer that the magnetic structure in bulk single crystals of VI₃ is complex, with magnetoelastic coupling being of significant importance.
[1] E. Gati et al., Phys. Rev. B 100, 094408 (2019) (Editor’s suggestion).