Dresden 2017 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 60: Correlated Electrons: f-Electron Systems

TT 60.8: Vortrag

Donnerstag, 23. März 2017, 11:30–11:45, HSZ 201

Direct bulk sensitive probe of 5f symmetry in URu₂Si₂ — Martin Sundermann¹, Maurits W Haverkort^2,4, 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 J_z =|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.