[Seminar] Coupled Trimer Description of Kagome Compound Volborthite
Dr. Tsutomu Momoi - RIKEN, Japan
Coupled Trimer Description of Kagome Compound Volborthite
Volborthite offers a stimulating example of a frustrated quantum magnet. It contains both ferromagnetic and antiferromagnetic interactions on anisotropic kagome layers. A density functional theory calculation has provided a magnetic model based on coupled trimers . This model shows a broad 1/3-magnetization plateau, which is consistent with the experimentally observed plateau behavior. This model also presents a scenario for the appearance of a spin nematic phase below the 1/3 plateau phase. Recently, we study the effects of Dzyaloshinskii-Moriya (DM) interactions in volborthite , deriving an effective spin model of S=1/2 pseudospins on trimers. We show that, for a magnetic field perpendicular to the kagome layer, magnon excitations from the 1/3-plateau feel a Berry curvature due to the DM interactions, giving rise to a thermal Hall effect. A comparison with the experiment suggests that the one-dimensionality is stronger than the previous estimation of exchange couplings. Based on this picture, we further analyze low-temperature magnetic phase diagrams.
 O. Janson, S. Furukawa, T. Momoi, P. Sindzingre, J. Richter, and K. Held, Phys. Rev. Lett. 117, 037206 (2016).
 S. Furukawa and T. Momoi, J. Phys. Soc. Jpn. 89, 034711 (2020).
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