Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 80: Correlated Electrons: (General) Theory 2
TT 80.9: Vortrag
Donnerstag, 10. März 2016, 18:15–18:30, H18
Rigorous Bounds on Pomeranchuk l=1 Instabilities from Ward Identities — •Egor Kiselev1, Mathias Scheurer1, Jörg Schmalian1,2, and Peter Wölfle1,3 — 1Institute for Theory of Condensed Matter, Karlsruhe Institute of Technology, 76049 Karlsruhe, Germany — 2Institute for Solid State Physics, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany — 3nstitut für Nanotechnologie, Karlsruher Institut für Technologie, D-76021 Karlsruhe, Germany
Pomeranchuk Instabilities signal spontaneous deformations of the Fermi surface. The shape of those deformations is parametrized by spherical harmonics Yl,0, so that Pomeranchuk Instabilities can be classified by the number l. In the l=1 case the Fermi surface is displaced by a small momentum and the instability results in spontaneously flowing spin or charge currents.
Using generalized Ward Identities it will be shown, that l=1 Pomeranchuk Instabilities in the spin/charge sector cannot be caused by a locally spin/charge conserving interaction respectively. Since the general case of Coulomb interaction between electrons and ions conserves electronic spin and charge, it is concluded that l=1 Pomeranchuk Instabilities can only occur, when relativistic physics is considered.
We discuss implications of our results for proposed emergent spin-orbit couplings, preemptive Pomeranchuk Instabilities near a ferromagnetic quantum critical point, and the low temperature Fermi liquid behaviour of 3He.