Electric Gruneisen parameters for a biaxial spin-chain system

The electric Gruneisen parameter, which characterizes the electrocaloric effect in the quantum spin system, has been introduced. We have calculated the electric Gruneisen parameter for the biaxial spin-chain system with strong coupling between the spin and the electric subsystems. It is shown that the low-temperature electric field dependence of the electric Gruneisen parameter manifests features at the critical values of the electric field and tends to constant at high temperatures. It is determined by the quantum critical points of the spin system. Such a behavior of the electric Gruneisen parameter can be observed in electrocaloric experiments with spin-chain materials.