A Quantum Spin Liquid (QSL) is a possible low temperature state for a magnetic system where quantum fluctuations prevent magnetic ordering, despite the presence of strong magnetic interactions that would normally lead to magnetic order. The concept of a QSL has intrigued scientists ever since it was introduced 40 years ago, sparking intrigue in both theorists and experimentalists alike. It is believed that these QSLs could have great potential applications within the field of quantum computing.
So far, it has proved difficult to create a QSL state within real materials experimentally, and so the characterisation of specific QSL phases has remained a great challenge. In previous experiments investigating QSL materials, the results have been interpreted with regards to just a single quantum phase, however, current theories indicate that in these frustrated spin models there are in fact many distinct quantum phases closely competing with one another.
In a new study of the layered QSL material 1T-TaS2, thermal measurements were used to study the energy distribution of the spin excitations and muon spin relaxation measurements were used to study the dynamical properties of these excitations. This study was a collaboration between Francis Pratt at the ISIS Neutron and Muon Source and the groups of Eugenio Coronado at the University of Valencia and Tom Lancaster at the University of Durham.
HiFi was used for these measurements due to its unique ability to measure very slow muon relaxation rates over an extended range of magnetic fields. By combining the temperature dependent muon spin relaxation and specific heat measurements for 1T-TaS2, it was possible to identify the character of the QSL phases present in the material. The results of the study support the existence of multiple QSL layers within the layered structure and competition between different QSL phases.