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TT: Fachverband Tiefe Temperaturen

TT 42: Correlated Electrons: f-Electron Systems and Heavy Fermions 2

TT 42.4: Vortrag

Mittwoch, 18. März 2020, 15:45–16:00, HSZ 204

A Resonant Inelastic X-ray Scattering investigation of the 4f states in SmB₆ — •Andrea Amorese^1,2, Oliver Stockert², Kurt Kummer³, Nicholas Brookes³, Maurits Haverkort⁴, Peter Thalmeier², Liu Hao Tjeng², and Andrea Severing¹ — ¹University of Cologne, Germany — ²MPI-CPfS, Dresden, Germany — ³ESRF, Grenoble, France — ⁴University of Heidelberg, Germany

The crystal-field (CF) splitting of the ⁶H_5/2 Hund’s rule ground state of Sm³⁺ in the strongly correlated topological insulator SmB₆ has been determined with high resolution resonant inelastic x-ray scattering (RIXS) at the Sm M₅ edge. The valence selectivity of RIXS allows isolating the crystal-field-split excited multiplets of the Sm³⁺ (4f⁵) configuration from those of Sm²⁺ (4f⁶) in intermediate valent SmB₆. We find that the quartet Γ₈ ground state and the doublet Γ₇ excited state are split by Δ_CF = 20±10meV. Considering this as an upper limit for the 4f bandwidth gives an extremely large mass renormalization from the band structure value, which can be linked to the small coefficient of fractional parentage for the hopping of the 4f electrons. The tiny band width complies with the small value of the gap and may be used to put constraints to the energies of the topological surface states. Financial support of the DFG under grant SE-1441/4-1 is acknowledged.