Quantum Spin Systems: Searching for the next materials revolution
Biography: Jason S Gardner is a condensed matter physicist and neutron scattering scientist with a specific interest in quantum beam experiments. For 15 years he has worked for several international user facilities, and visited many more. Dr Gardner is a Fellow of both the American Physical Society and the Institute of Physics (UK), Editor-in-Chief of the Journal of Physics: Condensed Matter and was most recently a Group Leader at the Australian Center for Neutron Scattering. He has published over 170 journal articles and given more than 100 oral presentations. He is a strong supporter for international collaborations and has brought many together at international conferences and scientific schools, national and international workshops that he has organized.
Abstract: Understanding the exotic electronic and magnetic properties of quantum materials, where classical physics cannot explain their physical properties has driven experimental physicists for years and is critical to the future of quantum data storage and quantum computing.
Recently a considerable amount of experimental effort has been put into finding new materials with a spin liquid ground state in which the electrons’ spins, much like the molecules in a liquid, are random and remain so all the way down to absolute zero. Geometrically frustrated magnetism is one avenue of exploration to reach this state.
In many materials, with a magnetic sublattice of corner sharing tetrahedra or triangles, the electrons’spins remain, at least partially random and dynamic. In this presentation I will present neutron scattering and low temperature thermodynamic properties of several kagome and pyrochlore materials which exhibit a significant amount of low energy spectral weight, or slow spin dynamics, even at 50mK. Although we can describe and parameterize many of the characteristics in these materials, we don't have a good starting model like those studying α-RuCl3. I will first discuss the classical spin ice state and its quasi-particle excitations (magnetic monopoles) before examining similar materials with massive quantum entanglement, resulting in a QSL. I will end by showing recent results on a new kagome material with fast Fe2+ spins at the lowest temperatures.
Because neutrons have their own magnetic moment but carry no charge, they are ideal for characterizing magnetic behavior in almost any material without compromising the material’s integrity. They are especially adept at characterizing how spins interact with each other through space and time, which are exactly the two things you need to distinguish between quantum spin liquid models.
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