Frustrated Magnetism in Mott Insulating V₂O₃

The phase diagram of V₂O₃ as function of transition metal doping and temperature is famous for showing transitions between metallic and insulating and between paramagnetic and antiferromagnetic phases. In particular, the Mott metal-insulator transition which is induced by a few percent of chromium doping has been studied intensively. Using a combination of density functional theory calculations and inelastic neutron scattering experiments, we study the magnetic interactions in the chromium-stabilized antiferromagnetic and paramagnetic insulating phases as function of temperature [1]. The calculations based on an energy mapping technique [2] are performed for low temperature monoclinic and high temperature rhombohedral structures. Both calculations and INS cross sections reveal significant magnetic frustration and degeneracy of the paramagnetic insulating phase which is relieved by the rhombohedral-to-monoclinic transition at T_N=185 K. Magnetic frustration can be shown to be present in rhombohedral (V_1−xCr_x)₂O₃ for a large range of dopings. This suggests that magnetic frustration plays an important role in suppressing the magnetic long-range-ordering temperature and thereby exposing a large phase space for the paramagnetic Mott metal-insulator transition.

Work done in collaboration with J. C. Leiner, R. Valentí, S. Zhang, A. T. Savici, J. Lin, M. B. Stone, M. D. Lumsden, J. Hong, O. Delaire, W. Bao, C. L. Broholm

[1] J. C. Leiner, H. O. Jeschke, R. Valentí, S. Zhang, A. T. Savici, J. Lin, M. B. Stone, M. D. Lumsden, J. Hong, O. Delaire, W. Bao, C. L. Broholm, Phys. Rev. X 9, 011035 (2019).
[2] D. Guterding, R. Valentí, H. O. Jeschke, Phys. Rev. B 94, 125136 (2016).