Magnetoelastic excitations in the pyrochlore spin liquid Tb2Ti2O7.
At low temperatures, Tb2Ti2O7 enters a spin liquid state, despite expectations of magnetic order and/or a structural distortion. Using neutron scattering, we have discovered that in this spin liquid state an excited crystal field level is coupled to a transverse acoustic phonon, forming a hybrid excitation. Magnetic and phononlike branches with identical dispersion relations can be identified, and the hybridization vanishes in the paramagnetic state. We suggest that Tb2Ti2O7 is aptly named a "magnetoelastic spin liquid" and that the hybridization of the excitations suppresses both magnetic ordering and the structural distortion. The spin liquid phase of Tb2Ti2O7 can now be regarded as a Coulomb phase with propagating bosonic spin excitations.
Laboratory for Neutron Scattering, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
T
T
Fennell
Laboratory for Developments and Methods, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
M
M
Kenzelmann
Laboratory for Neutron Scattering, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
B
B
Roessli
Institut Laue Langevin, BP 156, 6, rue Jules Horowitz, 38042 Grenoble Cedex 9, France.
H
H
Mutka
Institut Laue Langevin, BP 156, 6, rue Jules Horowitz, 38042 Grenoble Cedex 9, France.
J
J
Ollivier
Laboratory for Neutron Scattering, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
M
M
Ruminy
Laboratory for Neutron Scattering, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
U
U
Stuhr
Laboratory for Neutron Scattering, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
O
O
Zaharko
London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, 17-19 Gordon Street, London WC1H 0AH, United Kingdom.
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L
Bovo
Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
A
A
Cervellino
Department of Chemistry, Princeton University, Princeton, New Jersey 08540, USA.
M K
MK
Haas
Department of Chemistry, Princeton University, Princeton, New Jersey 08540, USA.
R J
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Cava