Colloquium Schedule

Colloquium: Thursday, October 17th, 4:25 PM, Lewis Lab 316

Anomalous Velocity and Geometry in Wave Mechanics

Eugene Mele

University of Pennsylvania
In electronic band theory the dynamics of electrons in crystal lattices can exhibit novel phenomena associated with the anomalous velocity.   Modern work on this subject revives an idea which appeared in its primitive form some fifty years ago to interpret the anomalous Hall effect in magnetically ordered states of matter, namely the appearance of a Hall conductivity in materials that have spontaneously broken time reversal symmetry without an applied magnetic field. The signature of the anomalous velocity is the coupling of electron motion to applied static and time-dependent fields through a family of transverse response functions with driving terms that are geometrical in origin.  This idea has been brought to the forefront by a modern focus on the topological nature of degenerate points and lines in the band structures of crystals and their observable consequences in electron dynamics.  Remarkably in this context the concept of anomalous velocity reappears with some unexpected  consequences for both  gapped “topological” states of matter and for special gapless topological semimetallic states. This talk will present a brief overview of these ideas and illustrate them with examples drawn from work on two dimensional electronic systems.

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Physics and Astronomy Colloquia are usually scheduled for Thursdays at 4:25 PM in Lewis Lab room 316. Refreshments and snacks are available in the nearby coffee room at 4:00 PM.


Physics Colloquium Schedule for Fall 2019

Click on Title below for past or upcoming Announcements (where available), and Speaker name for website.        

August 29---
September 5V. DobrosavljevicFlorida StateLandau Theory for Disorder-Driven Metal-Insulator
September 12Ivan BiaggioLehigh University The Life and Times of Excitons in an Organic "Semiconductor": Fission, Fusion, Entanglement, Transport, and Dissociation
September 19Cyrus DreyerStony BrookThe Modern Theory of Polarization with a Twist
September 26Martin ZwierleinMITThe Sound of Fermions
October 3A.L. ExarhosLafayetteCreating, Controlling, and Characterizing Quantum Emission from Hexagonal Boron Nitride
October 10Edmund WebbLehigh UniversityMultiscale Modeling of the Human Blood Protein Von Willebrand Factor
October 17Eugene MeleU. PennAnomalous Velocity and Geometry in Wave Mechanics
October 24Berndt MuellerBrookhaven NLThe Unbearable Burden of Being Light: Emergence of Ordinary Matter from Quarks and Gluons
October 31Chueng JiNCS University Proton Puzzle
Novemebr 7Gabriel KotliarRutgers UniversityTowards a Predictive Theory of Strongly Correlated Electron Materials
November 14Karen KaszaColumbia UniversityUnderstanding and controlling the mechanical behavior of living tissues inside developing embryos
November 21K. L. KnappenbergerPenn State UniversityStructural Influences on the Optical Properties Atomically Thin Metals
November 28Thanksgiving Break--
December 5Javier Perez-MorenoSkidmore College-