Abstracts 2002

Abstract of Publication No. 444

Ch. Rüegg, N. Cavadini, A. Furrer, K. Krämer, H. U. Güdel, P. Vorderwisch and H. Mutka
Spin dynamics in the high-field phase of quantum-critical S = 1/2 TlCuCl3
Appl. Phys. A 74, S840-S842 (2002)      Full Text (PDF)      DOI-Link     

Abstract: An external magnetic field suppresses the spin-energy gap in singlet ground state S=1/2 TlCuCl3. The system becomes quantum-critical at Hc 5.7 T, where the energy of the lowest Zeeman-split triplet excitation crosses the nonmagnetic ground state. Antiferromagnetic ordering is reported above Hc, which underlines the three-dimensional nature of the observed quantum phase transition. The intrinsic parameters of S=1/2 TlCuCl3 allow us to access the critical region microscopically by neutron scattering. A substantial study of the spin dynamics in the high-field phase of TlCuCl3 at T=1.5 K up to H=12 T was performed for the first time. The results possibly indicate two dynamical regimes, which can be understood within characteristically renormalized triplet modes and a low-lying dynamics of potentially collective origin.

Last modified: 13.12.11 by Gabriela Frei