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TT: Fachverband Tiefe Temperaturen

TT 81: Superconductivity: Properties and Electronic Structure

TT 81.4: Vortrag

Donnerstag, 3. April 2014, 10:15–10:30, HSZ 201

The high-energy anomaly in ARPES spectra of cuprates–many body or matrix element effect? — •J. Fink¹, E.D.L. Rienks², M. Ärrälä³, M. Lindroos³, F. Roth⁴, W. Tabis⁵, G. Yu⁵, and M. Greven⁵ — ¹Leibnitz-Institute for Solid State and Materials Research, Dresden, Germany — ²Helmholtz-Zentrum, Berlin, Germany — ³Tempere University of Technology, Tempere, Finland — ⁴Center for Free-Electron Laser Science, Hamburg, Germany — ⁵University of Minnesota, Mineapolis, USA

We used angle-resolved and polarization-dependent photoemission spectroscopy (ARPES) and density functional theory calculations to study the high-energy anomaly (HEA) in the dispersion of Nd_2−xCe_xCuO₄, x=0.123. We have found that at particular photon energies the anomalous, waterfall-like dispersion gives way to a broad, continuous band. This suggests that the HEA is a matrix element effect: it arises due to a local suppression of the intensity of the broadened quasiparticle band. We confirm this interpretation experimentally, by showing that a waterfall appears when the matrix element is suppressed deliberately by changing the light polarization. Calculations of the matrix element using atomic wave functions and simulation of the ARPES intensity with one-step calculations provides further proof for this scenario. The possibility to detect the full quasiparticle dispersion further allows us to extract the mass enhancement and the scattering rates at high binding energies at the center and edge of the Brillouin zone.