SKM 2023 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 9: f-Electron Systems and Heavy Fermions II

TT 9.5: Vortrag

Montag, 27. März 2023, 16:00–16:15, HSZ 201

U f² multiplet states in low energy excitations of UTe₂ — •Denise S. Christovam¹, Martin Sundermann^1,2, Andrea Marino¹, Daisuke Takegami¹, Johannes Falke¹, Paulius Dolmantas¹, Hlynur Gretarsson^2,3, Bernhard Keimer³, Priscila F. S. Rosa⁴, Andrea Severing^1,5, and Liu Hao Tjeng¹ — ¹MPI-CPfS, Dresden, Germany — ²DESY/PETRA-III, Hamburg, Germany — ³MPI-FKF, Stuttgart, Germany — ⁴LANL, Los Alamos, USA — ⁵Institute of Physics II, University of Cologne, Germany

Here we have investigated UTe₂, proposed to be a topological spin-triplet superconductor, with high-resolution resonant inelastic x-ray scattering (RIXS) at the U M_4,5 edges. Using this new experimental method, we can clearly observe the presence of U 5f atomic multiplet states in the low energy excitation spectrum of UTe₂. This establishes the correlated nature of the material and questions the applicability of band theory to describe quantitatively its electronic structure. We find that the observed multiplet structure belongs to the U⁴⁺ 5f² configuration. This is also surprising since half of the Te in this material have very short Te-Te distances, suggesting that half of the Te has a valence close to 1- rather than 2-, with the consequence that the U is expected to be 3+ rather than 4+. We speculate that the U 6d shell absorbs the extra charge, and that the local U charge configuration could be written as 5f²6d¹.