Title of the talk:
"Almost failed magnets: Ordered states on the brink of liquidity" - Professor Arun Paramekanti from the University of Toronto, Canada.
Abstract:
This is a story about solids which almost fail to magnetically order, where the crystal geometry or competing interactions lead to weak order with signs of spin liquidity found in their dynamical response. We will discuss examples from honeycomb and triangular magnets where numerical results and analytical methods can shed light on the phase diagrams and dynamical responses which can be observed in THz spectroscopy and inelastic neutron scattering experiments.
Title of the talk:
Emergent Guage Fields in Quantum Condensed Matter - Professor Steven Allan Kivelson (Stanford University)
Abstract:
It has long been understood that the exact (“fundamental”) gauge symmetry of the electromagnetic fields plays an important role in the theory of quantum materials. What has come into focus more recently is that there exist essential properties of quantum phases of matter that are best understood in terms of an effective field theory with emergent gauge fields, rather than (or in addition to) in terms of broken symmetries. Here, gauge invariance is not a symmetry of the microscopic problem but is rather an efficient representation of the low energy physics. I will review the well-known usefulness of this perspective in the context of such old friends as fractional quantum Hall fluids and a variety of ``spin-liquids.’’ As time permits, I will also discuss recent theoretical results that suggest that exotic “resonating valence-bond” fluids, describable by emergent gauge theories, might exist in a much broader range of experimentally accessible platforms than has been previously appreciated.