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R. G. Herb Condensed Matter Seminar
Dissipative mechanisms in SNS junctions and magnetic vortex lattices
Date: Thursday, February 1st
Time: 10:00 am
Place: 5310 Chamberlin
Speaker: Tony Liu, U Washington
Abstract: In superconductors there is a mechanism of dissipation which is related to the motion of quasiparticle energy levels and is similar to the Debye mechanism of microwave absorption in gases. The dissipation rate associated with this Debye-like mechanism is controlled by the inelastic relaxation time, and in some cases, it can dominate conventional dissipation mechanisms which are controlled by the elastic relaxation time. To illustrate this effect, I will discuss the role of this Debye-like mechanism in the I-V characteristics of SNS junctions as well as the microwave absorption of disordered magnetic vortex lattices. In the former, I will show that there is a new regime at small voltages/currents where the I-V characteristics are controlled entirely by the density of states in the SNS junction and are characterized by a large conductance proportional to the inelastic relaxation time. In the latter, I will show that the microwave absorption coefficient at small frequencies is similarly controlled by the inelastic relaxation time, and that it is significantly larger than the value obtained in the conventional Bardeen-Stephen picture.
Host: Alex Levchenko
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