Magentic-Field Induced Quantum Phase Transition and Critical Behavior in a Gapped Spin System TlCuCl$_3$
arXiv:cond-mat/0607439 · doi:10.1016/j.jmmm.2006.10.372
Abstract
Magnetization measurements were performed on TlCuCl$_3$ with gapped ground state. The critical density and the magnetic phase diagram were obtained. The interacting constant was obtained as $U/k_{\rm B} = 313$ K. The experimental phase boundary for $T < 5$ K agrees perfectly with the magnon BEC theory based on the Hartree-Fock approximation with realistic dispersion relations and $U/k_{\rm B} = 320 $ K. The exponent $Ï$ obtained with all the data points for $T < 5$ K is $Ï= 1.99$, which is somewhat larger than theoretical exponent $Ï_{\rm BEC} =3/2$. However, it was found that the exponent converges at $Ï_{\rm BEC} =3/2$ with decreasing fitting window.
2 pages, 2 figures, Submitted to Proceedings of International Conference on Magnetism (ICM2006)