Berlin 2024 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 18: Superconductivity: Poster

TT 18.22: Poster

Monday, March 18, 2024, 15:00–18:00, Poster C

Collective excitations in competing phases in two and three dimensions — •Joshua Althüser and Götz Uhrig — TU Dortmund, Otto-Hahn-Str. 4, 44227 Dortmund, Deutschland

We investigate the superconducting (SC), charge-density wave (CDW), and antiferromagnetic (AFM) phases in the extended Hubbard model at zero temperature and half-filling. We employ the iterated equations of motion approach [1,2] to compute the two-particle Green’s functions and by extension, the corresponding spectral densities. This renders a comprehensive analysis of the behaviour of collective excitations possible as the model’s parameters are changed across phase transitions. We identify the well-known amplitude (Higgs) and phase (Leggett) modes within the superconducting phase and observe a similar excitation in the CDW phase which shift towards zero energy as the system approaches the phase transition to the SC phase. In the CDW phase, close to the phase transition to the AFM phase, we find a collective mode which does not change significantly and another modes which becomes soft as the phase boundary is approached.

[1] P.Bleicker, G.S. Uhrig, Phys. Rev. A 98, 033602 (2018)

[2] M.Kalthoff, F. Keim, H. Krull, G.S. Uhrig, Eur. Phys. J. B 90, 97 (2017)

Keywords: Collective excitations; Competing phases; Superconductivity; Charge-density wave; Antiferromagnetism