Grüneisen parameters in the quantum paramagnet with the magnetoelectric coupling

Abstract

It is shown theoretically that magnetic Grüneisen parameter for the quantum orthorhombic paramagnet manifests features similar to the ones observed in many-body quantum spin systems at critical points. For the paramagnet with the strong coupling between the spin and electric subsystems, we have introduced the electric Grüneisen parameter, which is the characteristic of the electrocaloric effect in the system. The low-temperature behavior of both Grüneisen parameters is determined by the crossover points of the spectrum of the quantum paramagnet.