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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-2808
DTSTART:20121213T160000Z
DURATION:PT1H0M0S
DTSTAMP:20260412T060725Z
LAST-MODIFIED:20121127T210425Z
LOCATION:5310 Chamberlin
SUMMARY:Field-induced thermal transport in BEC antiferromagnets\, R. G
 . Herb Condensed Matter Seminar\, Sasha Chernyshev\, University of Cal
 ifornia\, Irvine
DESCRIPTION:Recent experiments in BEC quantum magnets exhibit a dramat
 ic evolution of the thermal conductivity of these materials in magneti
 c field. By considering various relaxation mechanisms of bosonic excit
 ations in the vicinity of the BEC quantum-critical point at finite tem
 perature we provide a detailed explanation of several unusual features
  of the data. We identify the leading impurity-scattering interaction 
 and demonstrate that its renormalization due to quantum fluctuations o
 f the paramagnetic state compensates the related mass renormalization 
 effect. This explains the enigmatic absence of the asymmetry between t
 he two critical points in the low-T thermal conductivity data\, while 
 such an asymmetry is prominent in many other physical quantities. The 
 observed characteristic "migration'' of the peak in thermal conductivi
 ty away from the transition points as a function of temperature is exp
 lained as due to a competition between an increase in the number of he
 at carriers and an enhancement of their mutual scattering. An importan
 t role of the three-boson scattering processes within the ordered phas
 e of these systems is also discussed. Other qualitative and quantitati
 ve features of the experiment are clarified and the future directions 
 are sketched. 
URL:https://www.physics.wisc.edu/events/?id=2808
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