Tunable magnon band topology and magnon orbital Nernst effect in noncollinear antiferromagnets

Abstract: We theoretically investigate the intrinsic magnon orbital Nernst effect (ONE) in noncollinear antiferromagnets with Kagom\'e spin systems. Our analysis reveals that an externally applied magnetic field induces topological phase transitions in the magnonic system, characterized by the closing and reopening of the band gap between distinct magnon bands. These transitions enable tunable control of the magnon orbital Nernst effect with applied magnetic field, with a pronounced enhancement in magnon orbital Nernst conductivity near the phase transition points. This tunability presents a promising direction for experimental detection of the magnon ONE.