Electric field induced thermal Hall effect of triplons in the quantum dimer magnets $X$CuCl$_{3}$ ($X =$ Tl, K)

We theoretically propose the electric field induced thermal Hall effect of triplons in the quantum dimer magnets $X$CuCl$_{3}$ ($X =$ Tl, K), which exhibit ferroelectricity in the Bose-Einstein condensation phase of triplons. The interplay between ferroelectricity and magnetism in these materials leads to the magnetoelectric effect, i.e., an electric-field induced Dzyaloshinskii-Moriya (DM) interaction between spins on the same dimer. We argue that this intradimer DM interaction breaks the symmetry of the system in the absence of an electric field and gives rise to the thermal Hall effect, which can be detected in experimentally accessible electric and magnetic fields. We also show that the thermal Hall effect can be controlled by changing the strength or direction of the electric field.
Comment: 20 pages, 9 figures, 2tables