Dresden 2011 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 7: SC: Properties, Electronic Structure, Mechanisms 2
TT 7.1: Vortrag
Montag, 14. März 2011, 14:00–14:15, HSZ 301
Importance of spin-orbit coupling for the electron-phonon interaction of the strong-coupling superconductor Pb — •Rolf Heid1, Klaus-Peter Bohnen1, Irina Sklyadneva2,1, and Evgeni Chulkov2 — 1Karlsruher Institut für Technologie, Institut für Festkörperphysik — 2Donostia International Physics Center, San Sebastian, Spain
Electron-phonon coupling (EPC) properties can nowadays be calculated
routinely from first principles within a DFT-based linear-response
approach. All previous studies, however, have been carried out in a
semi-relativistic framework, which does not take into account the effects of
spin-orbit coupling (SOC). Based on a recent implementation of the SOC
for linear response calculations within a mixed-basis pseudopotential
approach [1], we analyze the effect of SOC on the EPC for the prototype
strong-coupling superconductor Pb. We find that SOC increases the
coupling constant λ by 44%, solving the longstanding puzzle
of too small λ values obtained consistently in previous first
principles calculations. The origin of the SOC-induced enhancement
of λ lies both in a softening of the phonon spectrum and in
an increase of the EPC matrix elements, which significantly improves
the agreement with tunneling experiments. We also find a large
influence of SOC on phonon-induced electronic self-energies and lifetimes.
Finally, consequences for EPC properties of thin Pb films will be discussed.
R. Heid, K.-P. Bohnen, I. Yu. Sklyadneva, E. V. Chulkov,
Phys. Rev. B 81, 174527 (2010)