Faculté des sciences

Quantum magnets under pressure: controlling elementary excitations in TlCuCl₃

Rüegg, Ch. ; Normand, Bruce ; Matsumoto, M. ; Furrer, A. ; McMorrow, D. F. ; Krämer, K. W. ; Güdel, Hans-Ulrich ; Gvasaliya, S. N. ; Mutka, H. ; Boehm, M.

In: Physical Review Letters, 2008, vol. 100, p. 205701

We follow the evolution of the elementary excitations of the quantum antiferromagnet TlCuCl₃ through the pressure-induced quantum critical point, which separates a dimer-based quantum disordered phase from a phase of long-ranged magnetic order. We demonstrate by neutron spectroscopy the continuous emergence in the weakly ordered state of a low-lying but massive excitation corresponding to... Plus

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    Summary
    We follow the evolution of the elementary excitations of the quantum antiferromagnet TlCuCl₃ through the pressure-induced quantum critical point, which separates a dimer-based quantum disordered phase from a phase of long-ranged magnetic order. We demonstrate by neutron spectroscopy the continuous emergence in the weakly ordered state of a low-lying but massive excitation corresponding to longitudinal fluctuations of the magnetic moment. This mode is not present in a classical description of ordered magnets, but is a direct consequence of the quantum critical point