Investigation of thermal Hall conductivity in hexagonal LuFeO₃type multiferroics

Materials those exhibit electric and magnetic ordering simultaneously in their ground states and show electric field control of magnetism, may also exhibit novel/enhanced thermal Hall transport phenomena[Nat. Mater. 16, 797 (2017)] that have immense utilitarian worth in various device applications. In this study, we have investigated topology of the magnonic bands and the magnon-mediated thermal transport of the LuFeO₃ type novel multiferroics, in which the geometric origin of the ferroelectricity induced not only a net magnetization but also non-trivial magnetoelectric couplings [Nature Communications 5, 2998 (2014), Nature Materials 13, 163-167 (2014)]. We have employed the framework of linearized spin wave and linear response theories to study thermal conductivity as a function of the ferroelectric trimer lattice distortion. The calculated thermal Hall conductivity shows a non-trivial dependence on the ferroelectric distortion. We have also discussed the thermal transport in multiferroic LuFeO₃ and LuMnO₃ as case studies involving real materials