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Since the discovery of high-temperature superconductors in cuprates in 1986, many theoretical ideas have been proposed which have enriched condensed matter theory. Especially, the resonating valence bond (RVB) state for (doped) spin liquids is one of the most fruitful idea. In this talk, I would like to describe the development of RVB idea to broader class of materials, especially more conventional magnets. It is related to the noncollinear spin structures with spin chirality and associated quantal Berry phase applied to many phenomena and spintronics applications. It includes the (quantum) anomalous Hall effect, spin Hall effect, topological insulator, multiferroics, various topological spin textures, e.g., skyrmions, and nonlinear optics. I will show that even though the phenomena are extensive, the basic idea is rather simple and common in all of these topics.

Zoom: https://harvard.zoom.us/j/977347126

Many models in equilibrium statistical physics produce random fractal curves “at criticality.”  I will discuss one particular model, the loop-erased random walk, which is closely related to uniform spanning trees and Laplacian motion, and survey what is known today including some more recent results.  I will also discuss some of the important open problems and explain why the problem is hardest in exactly three dimensions. This talk is intended for a general mathematics audience and does not assume the audience knows the terms in the previous sentence.

Zoom: https://northeastern.zoom.us/j/95962897745?pwd=UFFPV2sxUitpWGFZbVErM1kwY284Zz09

For password email Andrew McGuinness