Multiple Magnetic Bilayers and Unconventional Criticality without Frustration in BaCuSi_{2}O_{6}.
- Allenspach S Neutrons and Muons Research Division, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
- Biffin A Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
- Stuhr U Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
- Tucker GS Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
- Ohira-Kawamura S J-PARC Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan.
- Kofu M J-PARC Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan.
- Voneshen DJ ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, United Kingdom.
- Boehm M Institut Laue Langevin, 6 Rue Jules Horowitz BP156, 38024 Grenoble Cedex 9, France.
- Normand B Neutrons and Muons Research Division, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
- Laflorencie N Laboratoire de Physique Théorique, CNRS and Université de Toulouse, 31062 Toulouse, France.
- Mila F Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
- Rüegg C Neutrons and Muons Research Division, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
- 2020-05-16
Published in:
- Physical review letters. - 2020
English
The dimerized quantum magnet BaCuSi_{2}O_{6} was proposed as an example of "dimensional reduction" arising near the magnetic-field-induced quantum critical point (QCP) due to perfect geometrical frustration of its interbilayer interactions. We demonstrate by high-resolution neutron spectroscopy experiments that the effective intrabilayer interactions are ferromagnetic, thereby excluding frustration. We explain the apparent dimensional reduction by establishing the presence of three magnetically inequivalent bilayers, with ratios 3∶2∶1, whose differing interaction parameters create an extra field-temperature scaling regime near the QCP with a nontrivial but nonuniversal exponent. We demonstrate by detailed quantum Monte Carlo simulations that the magnetic interaction parameters we deduce can account for all the measured properties of BaCuSi_{2}O_{6}, opening the way to a quantitative understanding of nonuniversal scaling in any modulated layered system.
- Language
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- English
- Open access status
- green
- Identifiers
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- DOI 10.1103/PhysRevLett.124.177205
- PMID 32412274
- Persistent URL
- https://sonar.ch/global/documents/1013
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