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TT: Fachverband Tiefe Temperaturen

TT 9: f-Electron Systems and Heavy Fermions II

TT 9.7: Talk

Monday, March 27, 2023, 16:30–16:45, HSZ 201

Evolution of the 4f states in TmSe_1−xTe_x from semimetals to semiconductors — •Chul Hee Min¹, Simon Müller², Michael Heber³, Lenart Dudy⁴, Hendrik Bentmann³, Matthias Kalläne¹, Markus Scholz³, Woojae Choi⁵, Yong Seung Kwon⁵, Friedrich Reinert², and Kai Rossnagel^1,3 — ¹IEAP, CAU Kiel, Germany — ²EP7 and ct.qmat, University of Würzburg, Germany — ³DESY, Hamburg, Germany — ⁴Synchrotron SOLEIL, Saint-Aubin, France — ⁵Dep. of EMS, DGIST, South Korea

Localized 4f states are often considered to become coherent states at low temperatures by hybridizing with itinerant conduction 5d states. In the standard Anderson model, only one type of interaction between the two states is taken into account, which is sufficient to describe Kondo physics. However, additional interaction has been suggested for the mixed valence regime to satisfy the Friedel sum rule when two charge states exist on a short time scale [1]. Here we present photoemission results of mixed-valent Thulium monochalcogenide TmSe_1−xTe_x. This system allows us to study the evolution of the localized 4f states between semimetallic and semiconducting phases without applying external pressure and disturbing the periodicity of Tm ions. Our results show two different interactions between 4f and 5d states across the phase transition.

[1] F. Haldane, Phys. Rev. B 15, 2477 (1976)

C. Varma, Phys. Rev. B 102, 155145 (2022)