% IMPORTANT: The following is UTF-8 encoded.  This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.

@PHDTHESIS{Mueller:639107,
      author       = {Mueller, Simon},
      othercontributors = {Reinert, Friedrich and Brunner, Karl},
      title        = {{I}ntermediate valence transition in epitaxial (111) films
                      of strongly correlated {T}hulium
                      monochalcogenides{Z}wischenvalenz-Übergänge in
                      epitaktischen (111) {F}ilmen aus stark korrelierten
                      {T}hulium-{M}onochalkogeniden},
      school       = {Julius-Maximilians-Universitaet Wuerzburg},
      type         = {Dissertation},
      address      = {Wuerzburg},
      publisher    = {Universität Würzburg},
      reportid     = {PUBDB-2025-04310},
      pages        = {158},
      year         = {2025},
      note         = {Dissertation, Julius-Maximilians-Universitaet Wuerzburg,
                      2024},
      abstract     = {Fundamental insights into complex quantum phases of
                      many-body systems can be ob-tained by the investigation of
                      the underlying particle interactions. The variety of
                      compet-ing interactions between particles involved
                      determines their behaviour in these quantumphases. In
                      strongly correlated electron systems the involved particles
                      are the localized4f-electrons and the itinerant
                      5d-electrons. Their interactions can lead to the
                      fascinatingintermediate valence phase of non-integer
                      f-occupation. In TmSe1−xTex this phase canbe induced by a
                      semiconductor-metal transition whose volume change already
                      indicates adrastic change in electron interaction. This
                      phase transition makes TmSe1−xTex suitableto investigate
                      the evolution of the electron interactions. The major issue
                      is the unavail-ability of TmSe1−xTex crystals within the
                      phase transition due to a miscibility gap justlocated around
                      the point of transition. In order to close this gap and
                      realize TmSe1−xTexcompounds throughout the whole
                      semiconductor-metal transition, the epitaxial growthof
                      TmSe1−xTex by molecular-beam epitaxy is chosen. The
                      advantage of this system isthe unique possibility to study
                      the evolution of the electron interactions by
                      photoemissionspectroscopy since the whole phase transition
                      and thus the emergence of intermediatevalence appears under
                      ambient conditions. Systematic investigations on this phase
                      tran-sition in epitaxial TmSe1−xTex have not yet been
                      realised by photoemission spectroscopywhich is therefore the
                      task of this work. For this purpose, a high quality
                      epitaxial growthof TmSe1−xTex is achieved on SrF2 (111)
                      which in addition opens a spectroscopic accessso far
                      unavailable by bulk single crystal cleavage. Two strategies
                      to obtain TmSe1−xTexphases throughout the phase transition
                      are investigated. Tuning the lattice parameters ofTmTe by
                      substrate-induced strain turns out to be not enough to reach
                      the phase transi-tion. A direct growth of thin TmSe1−xTex
                      films varying in xenables the investigation of theoverall
                      electronic structure across the phase transition although
                      the miscibility gap is notclosed by epitaxy. This includes
                      the first ever observed bandstructure of TmTe and TmSein the
                      (111) orientation. In the metallic phase of the transition a
                      constant f-occupation isobserved while in the semiconducting
                      phase the f-occupation seems to decrease towardsthe phase
                      transition. Drastic variations in the electronic
                      interactions are hereby displayedwhich are accompanied by
                      the observed gap opening. The detected separation of the
                      4f-state in the intermediate valence phase at temperatures
                      below 100 K is unexpected by theunderlying Anderson model.
                      It shows the possibly necessary inclusion of other
                      interac-tions among the electrons for the theoretical
                      description of intermediate valence systems.With these
                      results the basis for further investigations of electron
                      interactions in the inter-mediate valence system
                      TmSe1−xTex is given. The goal to provide spectroscopic
                      access bymolecular-beam epitaxy to phases throughout the
                      transition has not been ruled out.},
      cin          = {FS-SXQM},
      ddc          = {530 Physik},
      cid          = {I:(DE-H253)FS-SXQM-20190201},
      pnm          = {632 - Materials – Quantum, Complex and Functional
                      Materials (POF4-632) / 6G3 - PETRA III (DESY) (POF4-6G3) /
                      FS-Proposal: I-20231357 (I-20231357) / FS-Proposal:
                      I-20200225 (I-20200225)},
      pid          = {G:(DE-HGF)POF4-632 / G:(DE-HGF)POF4-6G3 /
                      G:(DE-H253)I-20231357 / G:(DE-H253)I-20200225},
      experiment   = {EXP:(DE-H253)P-P04-20150101 / EXP:(DE-H253)P-P08-20150101},
      typ          = {PUB:(DE-HGF)11},
      urn          = {urn:nbn:de:bvb:20-opus-404035},
      url          = {https://bib-pubdb1.desy.de/record/639107},
}