Van der Waals (vdW) materials are versatile systems for the study of magnetism in low dimensions. Motivated by the potential tunability of the new vdW ferromagnet VI3, a microscopic and thermodynamic study on bulk single crystals were performed under hydrostatic pressure using new techniques developed at Ames Laboratory. By combining the magnetization data with specific heat data under pressure and ambient-pressure NMR data we have shown that the critical pressure pc1 is not a result of a dimensional crossover but a triple point at which two phase transition lines merge. It is shown that the VI3 undergoes two ferromagnetic transitions, at ambient and low pressure, implying a complex magnetic structure. At higher pressures, the magnetic transitions merge with the structural phase transition, a hallmark of magnetoelastic coupling. Understanding and controlling such coupled transitions is critical for tuning magnetism for future device applications.
E. Gati, Y. Inagaki, T. Kong, R.J. Cava, Y. Furukawa, P.C. Canfield and S.L. Bud’ko, “Multiple ferromagnetic transitions and structural distortion in the van der Waals ferromagnet VI3 at ambient and finite pressures”, Physical Review B, 100, 094408 (2019) ; DOI: 10.1103/PhysRevB.100.094408 (Editor’s suggestion).