Regensburg 2019 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 49: Poster Session: Superconductivity
TT 49.6: Poster
Mittwoch, 3. April 2019, 15:00–18:30, Poster D
Toward the theory of the higher harmonic in superconducting gap dispersion of hole- and electron-doped cuprates — •Mikhail Malakhov1,2, Mikhail Eremin2, and Daniil Kochergin2 — 1Institut für Theoretische Physik III, Ruhr-Universität Bochum, Universitätsstraße 150, DE-44801 Bochum, Germany — 2Institute of Physics, Kazan Federal University, Kazan, 420008 Russia
Numerical solutions of the Bardeen-Cooper-Schrieffer equation are obtained, taking into account superexchange, three site correlation term, spin-fluctuation, plasmon, and phonon mediated mechanisms. Expression for charge and spin susceptibilities derived beyond RPA approximation. For both e- and h- doped cuprates at carrier concentrations close to optimal the energy gap dispersions where approximated by expression Δk=Δ0 (B cos(2φ) + (1−B) cos(6φ) ) , where the angle is measured from the antinodal direction in the Brillouin zone. In agreement with ARPES data we have got (1−B)>0 for h- doped cuprates and (1−B)<0 for e-doped one and right value of Δ0. In Bi2 Sr2 Ca Cu2 O8 we found that the amplitude before cos(6φ) is determined by spin-fluctuation and phonon mediated mechanisms. In case Pr0.89 La Ce0.11 Cu O4 the higher-harmonic is originated from spin-fluctuation and plasmon (Coulomb) pairing mechanisms. Numerically and analytically shown that role of three site correlations is weakening superexchange interaction.