University of Connecticut

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Condensed Matter Physics Seminar

Tuesday, November 14, 2017
2:00pm – 3:00pm

Storrs Campus
Physics Building, P121

Saikat Banerjee, Nordita, Stockholm, Sweden

Bosonic excitations in Dirac matter

The discovery of the Dirac dispersion of electrons in graphene led to a comprehensive investigation of a list compounds and quasiparticle bands with linear band touching. A unified description of this rapidly expanding list has brought forward the term Dirac materials. The stability of the Dirac cone with respect to interactions, emergence of different phases, and transient excitonic instabilities in optically-pumped Dirac materials are, to name a few, active areas of modern condensed matter physics. Within this extensive field of research, the concept of bosonic Dirac materials has emerged. In this talk, I discuss a few realizations of Dirac materials with bosonic excitations and describe the emergence of topological bosonic surface states and their differences from their fermionic counter-parts. The effects of interactions on reshaping the bosonic Dirac cone are discussed by considering a specific case of ferromagnets consisting of Van der Waals-bonded stacks of honeycomb layers. The relevance of bosonic Dirac theory is pointed out by qualitatively enplaning an unexplained anomaly in magnetic neutron scattering data of CrBr3 from 1970. I also mention an interesting situation where the Dirac bosons have long-range coherence (form a Bose-Einstein condensate) and the difference between the dynamics of the Dirac condensate and the conventional analogue described by the Gross-Pitaevskii equation.


Prof. J. Hancock

Physics Department (primary), UConn Master Calendar

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