Dresden 2017 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 39: Superconductivity: (General) Theory
TT 39.4: Vortrag
Mittwoch, 22. März 2017, 10:15–10:30, HSZ 103
Charge and current orders in the cuprates: implications from spin-fermion model with overlapping hot spots. — •Pavel A. Volkov and Konstantin B. Efetov — Theoretische Physik III, Ruhr-Universität Bochum, D-44780 Bochum, Germany
Experiments carried over the last years on the underdoped cuprates suggest the presence of a variety of symmetry-breaking phenomena in the pseudogap phase. Charge-density waves, breaking of C4 rotational symmetry, as well as time-reversal symmetry breaking have all been observed in several cuprate families. Unification of these phenomena thus poses a crucial theoretical challenge. We address this issue in the framework of the spin fluctuation scenario, where the low-energy fermions interact through the exchange of antiferromagnetic fluctuation quanta, paramagnons. We study particle-hole instabilities in a model explicitly taking into account two regions of the Fermi surface: around (0,π) and (π,0). For a quasi-1D dispersion in both regions, we show that for sufficiently small |ε (π ,0)−EF|, the leading instability is a d-form factor Fermi surface deformation (Pomeranchuk instability). It naturally produces a C4-breaking and supports the formation of a unidirectional bond-oriented d-form factor CDW at lower temperatures, consistent with experiments. Additionally, we show that the Fermi surface curvature in the antinodal regions promotes a state formed by current loops organized in an antiferromagnetic structure (as in the d-density wave state), and thus breaking time-reversal symmetry.