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