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Thermodynamics of the coupled spin-dimer system TlCuCl3 close to a quantum phase transition

T. Lorenz·S. Stark·O. Heyer·N. Hollmann·A. Vasiliev·A. Oosawa·H. Tanaka
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Abstract

We present thermal expansion alpha, magnetostriction and specific heat C measurements of \tal, which 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. Using Ehrenfest's relation, we find huge pressure dependencies of the spin gap for uniaxial as well as for hydrostatic pressure. For T->0 and H->H_{C0} we observe a diverging Grueneisen parameter Gamma(T)=alpha/C, in qualitative agreement with theoretical predictions. However, the predicted individual temperature dependencies alpha(T) and C(T) are not reproduced by our experimental data.

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T. Lorenz, S. Stark, O. Heyer, N. Hollmann, A. Vasiliev, A. Oosawa, H. Tanaka. 2006-09-14. Thermodynamics of the coupled spin-dimer system TlCuCl3 close to a quantum phase transition. https://doi.org/10.1016/j.jmmm.2007.02.154

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