Magnetothermal properties of honeycomb ferromagnet CrGeTe₃

CrGeTe₃ has been investigated as a prototypical semiconducting layered van der Waals ferromagnet with a transition temperature of T_C = 61 K. The magnetic sublattice is composed of spin 3/2 Cr atoms on a 2D honeycomb lattice within which the Kitaev interaction is thought to play an important role. We report the physical properties of single crystals of CrGeTe₃ grown with a self flux method focusing on magnetothermal effects. We observe an acute sensitivity of both specific heat and thermal transport to applied magnetic fields that evolves rapidly across magnetic ordering. We analyze this response in terms of phonon and spin excitations and find evidence for a significant role of both magnons and magnon-phonon coupling. We compare these results with expectations for the proposed magnetic Hamiltonian for the honeycomb network in this material.