Neutron scattering and mu SR investigations of the low temperature state of LuCuGaO4

Summary, in English

LuCuGaO4 has magnetic Cu2+ and diamagnetic Ga3+ ions distributed on a triangular bilayer and is suggested to undergo a spin glass transition at T-g similar to 0.4 K. Using mu SR (muon spin rotation) and neutron scattering measurements, we show that at low temperature the spins form a short range correlated state with spin fluctuations detectable over a wide range of timescales: at 0.05 K magnetic fluctuations can be detected in both the mu SR time window and also extending beyond 7 meV in the inelastic neutron scattering response, indicating magnetic fluctuations spanning timescales between similar to 10(-5) and similar to 10(-10) s. The dynamical susceptibility scales according to the form chi '' (omega)T-alpha, with alpha = 1, throughout the measured temperature range (0.05-50 K). These effects are associated with quantum fluctuations and some degree of structural disorder in ostensibly quite different materials, including certain heavy fermion alloys, kagome spin liquids, quantum spin glasses, and valence bond glasses. We therefore suggest that LuCuGaO4 is an interesting model compound for the further examination of disorder and quantum magnetism.

• Author: S. Calder; S. R. Giblin; D. R. Parker; Pascale Deen; C. Ritter; J. R. Stewart; S. Rols; T. Fennell
• Department/s: European Spallation Source ESS AB
• Publishing year: 2013
• Language: English
• Publication/Series: Journal of Physics: Condensed Matter
• Volume: 25
• Issue: 35
• Links: http://dx.doi.org/10.1088/0953-8984/25/35/356002
• Document type: Journal article
• Publisher: IOP Publishing
• Topic: Natural Sciences; Physical Sciences
• Status: Published
• ISBN/ISSN/Other: ISSN: 1361-648X