Since 2002 Perimeter Institute has been recording seminars, conference talks, and public outreach events using video cameras installed in our lecture theatres. Perimeter now has 7 formal presentation spaces for its many scientific conferences, seminars, workshops and educational outreach activities, all with advanced audio-visual technical capabilities. Recordings of events in these areas are all available On-Demand from this Video Library and on Perimeter Institute Recorded Seminar Archive (PIRSA). PIRSA is a permanent, free, searchable, and citable archive of recorded seminars from relevant bodies in physics. This resource has been partially modelled after Cornell University's arXiv.org.
I will discuss a new duality between strongly coupled and weakly coupled condensed matter systems. It can be obtained by combining the gauge-gravity duality with analog gravity. In my talk I will explain how one arrives at the new duality, what it can be good for, and what questions this finding raises.
It has been recently established that a magnetized relativistic plasma yields an interesting example of a Weyl metal. I discuss the properties of magnetized relativistic plasma and its possible role in some astrophysics phenomena.
Our search for new materials of (hopeful) relevance to materials physics is wide ranging. One of our primary interests is in finding new geometrically frustrated magnets and working on their structure-property relations. In this context in recent years we have found and grown crystals of a new class of pyrochlore magnets based on fluorine instead of oxygen. This chemical difference allows pyrochlores to be made with magnetic transition metals on the “B sites”, and non-magnetic ions on the A sites, which results in stronger magnetic coupling than is seen in the rare earth pyrochlores.
Double perovskites, a class of oxide materials with 3d and 5d transition metal ions, can realize a wide variety of interesting phases. Here we focus on our recent theoretical work suggesting the appearance of Chern insulators, and possible emergent nematic phases at Chern transitions in such systems. We will also discuss Mott insulating double perovskites with iridium moments which appear to host unusual magnetic interactions on the 3-dimensional fcc lattice, and present comparisons with experimental data.
Muon spin rotation/relaxation is a powerful technique for studying unconventional superconductors, whose order parameter doesn't have the same symmetry as its host material's crystal structure. I will describe our work on Sr2RuO4, UPt3, CuxBi2Se3 and other topical systems, some of which exhibit broken time reversal symmetry in their superconducting states.
A series of fundamental discoveries over the past thirty years has dramatically improved our ability to read, write, and process magnetically stored information. I will briefly review some of these advances before focusing on the recently discovered and particularly promising spin-orbit torques which act on the collective spin of thin film magnetic conductors when they are placed on a substrate with strong spin-orbit interactions. Spin-orbit torques are normally interpreted in terms of the spin Hall effect, spin-current that flows perpendicular to charge current in any conductor.
The spatially-indirect exciton condensates (SIXC) is an interesting ordered electronic state in which coherence is spontaneously established between particles localized in separate two-dimensional layers. I will discuss some of the properties SIXCs, commenting on their counterflow superfluidity, their collective excitations, and on similarities and differences relative to superconductors, easy-plane ferromagnets and anti-ferromagnets, and the standard model of particle physics.
The standard theory of topological insulators and superfluids (or superconductors) assumes that the fermionic elementary excitations in these systems – electrons in the insulator and Bogoliubov quasiparticles in the superfluid – do not interact with one another. In this talk I will discuss extensions of this theory to include the effects of interparticle interactions on the topological surface states of 3D topological insulators and superfluids.
It is well known - to those who know it - that noise and randomness can enhance signal resolution. I'll present an easy-to-follow example from digital audio that illustrates the way in which adding noise ("dither") prior to measurement enhances the accuracy with which we are able to distinguish the features of the sound or image. I will then explore the way in which the environmental interactions prior to measurement ordinarily characterized as environment-induced decoherence may play a similar role.