Magnon Nernst Effect in Magnon Spin Hall Systems

Magnon spin Hall systems could hardly show experimentally observable particle and thermal transport phenomena intrinsically due to the spin cancellation. Here we demonstrated that the magnon spin Hall systems can exhibit magnon Nernst effect and thermal Hall effect under external magnetic field by considering two typical systems, i.e. the antiferromagnetically (AFM) coupled bilayer honeycomb ferromagnets and monolayer collinear honeycomb antiferromagnet. The both systems experience magnetic phase transitions from AFM phase to a field-polarized phase via a spin-flop (SF) phase or directly. In both systems, there exist magnon Nerst effect and also thermal Hall effect under a longitudinal temperature gradient, which can be regarded as the indicator of the magnetic phase transitions, with the Hall conductivity dependence on magnetic field consistent with the order of magnetic phase transition.