Thermodynamic properties of the field-induced Neel order of TlCuCl3

TL;DR

This paper investigates the thermodynamic behavior of TlCuCl3 near its quantum phase transition, revealing divergence in the Grueneisen parameter consistent with theory, but discrepancies in specific heat and thermal expansion data.

Contribution

It provides experimental measurements of thermodynamic properties near the quantum critical point, highlighting partial agreement and discrepancies with theoretical predictions.

Findings

Divergence of Grueneisen parameter near critical field

Qualitative agreement with theoretical divergence

Discrepancies in individual thermal expansion and specific heat behaviors

Abstract

TlCuCl3 shows a quantum phase transition from a spin-gap phase to a Neel-ordered ground state as a function of magnetic field around H_{C0}~4.8T. From measurements of the specific heat c and the linear thermal expansion alpha_i we calculate the Grueneisen parameter Gamma_i(T)=alpha_i/c. Close to H_{C0} we find a diverging Gamma_i(T->0, in qualitative agreement with theoretical predictions. However, the predicted individual temperature dependencies of alpha(T) and c(T) are not reproduced by our experimental data.