Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 13: Electronic structure II

O 13.2: Vortrag

Montag, 23. März 2009, 15:15–15:30, SCH A216

Temperature dependent quasiparticle renormalization in nickel metal — •Ruslan Ovsyannikov, Jaime Sánchez-Barriga, Jörg Fink, and Hermann A. Dürr — Helmholtz Zentrum Berlin, BESSY II, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany

One of the fundamental consequences of electron correlation effects is that the bare particles in solids become ’dressed’, i.e. they acquire an increased effective mass and a lifetime. We studied the spin dependent quasiparticle band structure of Ni (111) with high resolution angle resolved photoemission spectroscopy. At low temperatures (50 K) a renormalization of quasiparticle energy and lifetime indicative of electron-phonon coupling is observed in agreement with literature [1]. With increasing temperature we observe a decreasing quasiparticle lifetime at the Fermi level for all probed minority spin bands as expected from electron phonon coupling. Surprisingly the majority spin states behave differently. We actually observe a slightly increased lifetime at room temperature. The corresponding increase in Fermi velocity points to a temperature dependent reduction of the majority spin quasiparticle renormalization.

[1] M. Higashiguchi et al., Phys. Rev. B 72, 214438 (2005)