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TT: Fachverband Tiefe Temperaturen

TT 85: Superconductivity: Higgs Modes in Condensed Matter and Quantum Gases (jointly with DY, MA, O)

TT 85.4: Vortrag

Donnerstag, 19. März 2015, 10:30–10:45, H 2053

Magnon-Interactions and Higgs Mode in 2D Quantum Antiferromagnets from Raman Scattering — •Simon Weidinger and Wilhelm Zwerger — Physik-Department, Technische Universität München, 85747 Garching, Deutschland

We present a theory for Raman scattering on 2D quantum antiferromagnets. The microscopic Fleury-Loudon Hamiltonian is expressed in terms of an effective O(3)- model. Well within the Neel ordered phase, the Raman spectrum contains both a two-magnon and two-Higgs contribution which are calculated diagrammatically. The spectrum is dominated by a broad two-magnon peak but it is hardly affected by the Higgs-mode of the 2D Neel ordered state. This is a consequence of the momentum dependence of the Raman vertex in the relevant B_1g symmetry. The resulting nontrivial spectrum, which has the antiferromagnetic exchange coupling as a single parameter, is in very good agreement with experiments on undoped cuprates.