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Quantum Matter Seminar

Wednesday, March 9, 2022
4:00pm to 5:00pm
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East Bridge 201 (Richard P. Feynman Lecture Hall)
Spin-chiral fluctuation processes in magnetic insulators and metals
Max Hirschberger, The University of Tokyo,

Chirality is an ubiquitous concept in the natural sciences, distinguishing left- and right-handed objects or processes. In magnetic solids, the chirality of spin textures is derived from the twisting

habit of neighboring atomic spins. I will discuss dynamical processes, specifically thermal fluctuation processes, which are transient but generate a net chiral habit in a magnetic solid. Through their coupling to local magnetic moments, conduction electrons feel this chiral habit;

hence, (thermo-) electric transport coefficients, which are time-averaged quantities, allow us to distinguish two scenarios: (1) Short-range spin correlations, where a small cluster of magnetic moments is sufficient to describe the physical properties of the thermally disordered solid and (2) Longer-range correlations, such as dynamically nucleating and decaying skyrmions. I introduce toy model systems which realize Kagome and triangular lattices of magnetic moments, and discuss the role of lattice geometry in promoting these fluctuation phenomena. Finally, I will show that the thermal Hall effect of magnetic insulators can also have a contribution related to thermal fluctuations of spin-chiral nature.

For more information, please contact Tracy Mikuriya by email at [email protected].