Magnon gap mediated lattice thermal conductivity in MnBi2Te4

In magnetic materials with strong spin-lattice coupling, magnon-phonon interactions can change the sensitivity of the lattice thermal conductivity in an applied magnetic field. Applying an out-of-plane magnetic field to change MnBi2Te4 between antiferromagnetic (AFM), canted antiferromagnetic (CAFM), and ferromagnetic (FM) phases, we controlled the lattice thermal conductivity, generating both a positive and a negative magnetic field dependence. The in-plane thermal conductivity decreases with field in the AFM phase, remains approximately constant in the CAFM phase, and increases with field in the FM phase. We explain this in terms of the field-induced changes of the magnon gap which modifies magnon-phonon scattering. We also report thermal Hall data measured in the same configuration.

Automated summary

In magnetic materials with strong spin-lattice coupling, the sensitivity of the lattice thermal conductivity to an applied magnetic field can be changed by magnon-phonon interactions. This study demonstrates the control of lattice thermal conductivity by changing the magnetic phases of MnBi2Te4 through the application of a magnetic field. Different magnetic phases exhibit different responses of the lattice thermal conductivity to the magnetic field.