Dresden 2017 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 60: Correlated Electrons: f-Electron Systems
TT 60.8: Talk
Thursday, March 23, 2017, 11:30–11:45, HSZ 201
Direct bulk sensitive probe of 5f symmetry in URu2Si2 — Martin Sundermann1, Maurits W Haverkort2,4, Mark Golden3, Yinkai Huang3, Anne de Visser3, Peter Thalmeier2, Liu Hao Tjeng2, and •Andrea Severing1 — 1University of Cologne, Institute of Physics II, 50937 Cologne, Germany — 2Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany — 3Van der Waals-Zeeman Institute, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands — 4present address: Institute for Theoretical Physics, Heidelberg University, 69120 Heidelberg, Germany
The order parameter of the second-order phase transition into a hidden order phase in URu2Si2 is still a mystery, despite 30 years of research. However, it is understood that the symmetry of the order parameter must be related to the symmetry of the low lying local electronic f-states. Here we present results of a novel spectroscopy, namely core-level non-resonant inelastic x-ray scattering (NIXS). This method allows for the measurement of local high-multipole excitations and it is bulk sensitive. The observed anisotropy of the scattering function unambiguously shows that the 5f ground state wave function is composed mainly of the Γ1 with majority Jz =|4⟩ + |−4⟩ and/or Γ2 singlet states. The incomplete dichroism indicates the superposition of quantum states necessary for constructing the HO state with the breaking of the fourfold symmetry.