Quantum magnets under pressure: controlling elementary excitations in TlCuCl3.
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.
Rüegg
Ch
Ch
London Centre for Nanotechnology, University College London, London WC1E 6BT, United Kingdom.
Normand
B
B
Matsumoto
M
M
Furrer
A
A
McMorrow
D F
DF
Krämer
K W
KW
Güdel
H-U
HU
Gvasaliya
S N
SN
Mutka
H
H
Boehm
M
M