  Thermal switching materials, whose thermal conductivity can be controlled
externally, show great potential in contemporary thermal management.
Manipulating thermal transport properties through magnetic fields has been
accomplished in materials that exhibit a high magnetoresistance. However, it is
generally understood that the lattice thermal conductivity attributed to
phonons is not significantly impacted by the magnetic fields. In this study, we
experimentally demonstrate the significant impact of phonon-magnon scattering
on the thermal conductivity of the rare-earth metal gadolinium near room
temperature, which can be controlled by a magnetic field to realize thermal
switching. Using first-principles lattice dynamics and spin-lattice dynamics
simulations, we attribute the observed change in phononic thermal conductivity
to field-suppressed phonon-magnon scattering. This research suggests that
phonon-magnon scattering in ferromagnetic materials is crucial for determining
their thermal conductivity, opening the door to innovative
magnetic-field-controlled thermal switching materials.
