Dresden 2003 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 3: Supraleitung: Elektronenstruktur, Phononen, Tunneln, Ordnungsparameter I
TT 3.12: Vortrag
Montag, 24. März 2003, 12:15–12:30, HSZ301
Relaxation of Hot Quasiparticles in a d-wave Superconductor — •Philip Howell1, Achim Rosch1, and Peter Hirschfeld2 — 1Institut für Theorie der Kondensierten Materie, Universität Karlsruhe, 76128 Karlsruhe — 2Department of Physics, University of Florida, Gainesville, FL 32611-8440, USA
In recent low temperature experiments on YBCO [1] quasiparticles with energy of order the gap have been produced which relax extremely slowly, with a temperature-dependent scattering rate. This motivates us to consider the processes by which ‘hot’ quasiparticles near the antinodes can relax to their equilibrium position near the nodes. We show that in a large region of momentum space processes which break Cooper pairs are forbidden by the requirements of momentum conservation, and therefore that equilibrium occurs by scattering with thermal quasiparticles at the nodes. The momentum transferred in each scattering event is then determined by temperature and is small, leading to a picture of quasiparticles diffusing in momentum space towards the gap nodes. We find the temperature dependence of this diffusive rate to vary as T4 in the asymptotically low-T regime T≪ Δ03/EF2, where Δ0 is the gap maximum and EF the Fermi energy. In the physically more relevant intermediate regime Δ03/EF2≪ T≪ Δ02/EF we discuss estimates of new scattering and pairbreaking processes which contribute. Finally, we discuss estimates for the intensity dependence of the antinodal diffusion rate.
[1] G.P. Segre, N. Gedik, J. Orenstein, D.A. Bonn, R. Liang, and W.N. Hardy, Phys. Rev. Lett. 88, 137001 (2002).