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Field-induced thermal transport in BEC antiferromagnets

Speaker: 
Alexander L. Chernyshev
Date: 
Wed, 18/09/2013 - 3:00pm to 4:00pm
Location: 
S13-M01-11 (Physics Conference Room)
Host: 
Antonio Castro Neto
Event Type: 
Seminars

Abstract:

After a highly biased, but historical introduction into thermal transport in insulating magnets, I shall attempt a brief and not legally binding remarks on the theory of this phenomenon in a subclass of antiferromagnets referred to as the BEC antiferromagnets. Terminology will be introduced and experiments will be explained.

Recent experiments in BEC quantum magnets exhibit a dramatic evolution of the thermal conductivity in magnetic field. We provide a detailed explanation of several unusual features of the data. We identify the leading impurity-scattering interaction and demonstrate that its renormalization explains the enigmatic absence of the asymmetry in the low-T thermal conductivity data, while such an asymmetry is prominent in many other physical quantities. The observed "migration'' of the thermal conductivity peak away from the transition points vs temperature is explained as due to a competition between an increase in the number of heat carriers and an enhancement of their mutual scattering. An important role of the three-boson scattering processes in these systems is also discussed.

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