@article{WurdackLundtKlaasetal.2017,
  author    = {Wurdack, Matthias and Lundt, Nils and Klaas, Martin and Baumann, Vasilij and Kavokin, Alexey V. and H{\"o}fling, Sven and Schneider, Christian},
  title     = {Observation of hybrid Tamm-plasmon exciton-polaritons with GaAs quantum wells and a MoSe\(_{2}\) monolayer},
  series = {Nature Communications},
  volume    = {8},
  journal   = {Nature Communications},
  number    = {259},
  doi       = {10.1038/s41467-017-00155-w},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170480},
  year      = {2017},
  abstract  = {Strong light matter coupling between excitons and microcavity photons, as described in the framework of cavity quantum electrodynamics, leads to the hybridization of light and matter excitations. The regime of collective strong coupling arises, when various excitations from different host media are strongly coupled to the same optical resonance. This leads to a well-controllable admixture of various matter components in three hybrid polariton modes. Here, we study a cavity device with four embedded GaAs quantum wells hosting excitons that are spectrally matched to the A-valley exciton resonance of a MoSe\(_{2}\) monolayer. The formation of hybrid polariton modes is evidenced in momentum resolved photoluminescence and reflectivity studies. We describe the energy and k-vector distribution of exciton-polaritons along the hybrid modes by a thermodynamic model, which yields a very good agreement with the experiment.},
  language  = {en}
}
@article{WaldherrLundtKlaasetal.2018,
  author    = {Waldherr, Max and Lundt, Nils and Klaas, Martin and Betzold, Simon and Wurdack, Matthias and Baumann, Vasilij and Estrecho, Eliezer and Nalitov, Anton and Cherotchenko, Evgenia and Cai, Hui and Ostrovskaya, Elena A. and Kavokin, Alexey V. and Tongay, Sefaattin and Klembt, Sebastian and H{\"o}fling, Sven and Schneider, Christian},
  title     = {Observation of bosonic condensation in a hybrid monolayer MoSe2-GaAs microcavity},
  series = {Nature Communications},
  volume    = {9},
  journal   = {Nature Communications},
  doi       = {10.1038/s41467-018-05532-7},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-233280},
  year      = {2018},
  abstract  = {Bosonic condensation belongs to the most intriguing phenomena in physics, and was mostly reserved for experiments with ultra-cold quantum gases. More recently, it became accessible in exciton-based solid-state systems at elevated temperatures. Here, we demonstrate bosonic condensation driven by excitons hosted in an atomically thin layer of MoSe2, strongly coupled to light in a solid-state resonator. The structure is operated in the regime of collective strong coupling between a Tamm-plasmon resonance, GaAs quantum well excitons, and two-dimensional excitons confined in the monolayer crystal. Polariton condensation in a monolayer crystal manifests by a superlinear increase of emission intensity from the hybrid polariton mode, its density-dependent blueshift, and a dramatic collapse of the emission linewidth, a hallmark of temporal coherence. Importantly, we observe a significant spin-polarization in the injected polariton condensate, a fingerprint for spin-valley locking in monolayer excitons. Our results pave the way towards highly nonlinear, coherent valleytronic devices and light sources.},
  language  = {en}
}
@article{StuehlerKowalewskiReisetal.2022,
  author    = {St{\"u}hler, R. and Kowalewski, A. and Reis, F. and Jungblut, D. and Dominguez, F. and Scharf, B. and Li, G. and Sch{\"a}fer, J. and Hankiewicz, E. M. and Claessen, R.},
  title     = {Effective lifting of the topological protection of quantum spin Hall edge states by edge coupling},
  series = {Nature Communications},
  volume    = {13},
  journal   = {Nature Communications},
  doi       = {10.1038/s41467-022-30996-z},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-300886},
  year      = {2022},
  abstract  = {The scientific interest in two-dimensional topological insulators (2D TIs) is currently shifting from a more fundamental perspective to the exploration and design of novel functionalities. Key concepts for the use of 2D TIs in spintronics are based on the topological protection and spin-momentum locking of their helical edge states. In this study we present experimental evidence that topological protection can be (partially) lifted by pairwise coupling of 2D TI edges in close proximity. Using direct wave function mapping via scanning tunneling microscopy/spectroscopy (STM/STS) we compare isolated and coupled topological edges in the 2D TI bismuthene. The latter situation is realized by natural lattice line defects and reveals distinct quasi-particle interference (QPI) patterns, identified as electronic Fabry-P{\´e}rot resonator modes. In contrast, free edges show no sign of any single-particle backscattering. These results pave the way for novel device concepts based on active control of topological protection through inter-edge hybridization for, e.g., electronic Fabry-P{\´e}rot interferometry.},
  language  = {en}
}
@article{ShamimMahapatraScappuccietal.2017,
  author    = {Shamim, Saquib and Mahapatra, S. and Scappucci, G. and Klesse, W. M. and Simmons, M. Y. and Ghosh, Arindam},
  title     = {Dephasing rates for weak localization and universal conductance fluctuations in two dimensional Si: P and Ge: P δ-layers},
  series = {Scientific Reports},
  volume    = {7},
  journal   = {Scientific Reports},
  number    = {46670},
  doi       = {10.1038/srep46670},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170934},
  year      = {2017},
  abstract  = {We report quantum transport measurements on two dimensional (2D) Si:P and Ge:P δ-layers and compare the inelastic scattering rates relevant for weak localization (WL) and universal conductance fluctuations (UCF) for devices of various doping densities (0.3-2.5 × 10\(^{18}\)m\(^{-2}\)) at low temperatures (0.3-4.2 K). The phase breaking rate extracted experimentally from measurements of WL correction to conductivity and UCF agree well with each other within the entire temperature range. This establishes that WL and UCF, being the outcome of quantum interference phenomena, are governed by the same dephasing rate.},
  language  = {en}
}
@article{SchneiderGlazovKornetal.2018,
  author    = {Schneider, Christian and Glazov, Mikhail M. and Korn, Tobias and H{\"o}fling, Sven and Urbaszek, Bernhard},
  title     = {Two-dimensional semiconductors in the regime of strong light-matter coupling},
  series = {Nature Communications},
  volume    = {9},
  journal   = {Nature Communications},
  doi       = {10.1038/s41467-018-04866-6},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-231295},
  year      = {2018},
  abstract  = {The optical properties of transition metal dichalcogenide monolayers are widely dominated by excitons, Coulomb-bound electron-hole pairs. These quasi-particles exhibit giant oscillator strength and give rise to narrow-band, well-pronounced optical transitions, which can be brought into resonance with electromagnetic fields in microcavities and plasmonic nanostructures. Due to the atomic thinness and robustness of the monolayers, their integration in van der Waals heterostructures provides unique opportunities for engineering strong light-matter coupling. We review first results in this emerging field and outline future opportunities and challenges.},
  language  = {en}
}
@article{LundtKlembtCherotchenkoetal.2016,
  author    = {Lundt, Nils and Klembt, Sebastian and Cherotchenko, Evgeniia and Betzold, Simon and Iff, Oliver and Nalitov, Anton V. and Klaas, Martin and Dietrich, Christof P. and Kavokin, Alexey V. and H{\"o}fling, Sven and Schneider, Christian},
  title     = {Room-temperature Tamm-plasmon exciton-polaritons with a WSe\(_{2}\) monolayer},
  series = {Nature Communications},
  volume    = {7},
  journal   = {Nature Communications},
  doi       = {10.1038/ncomms13328},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-169470},
  year      = {2016},
  abstract  = {Solid-state cavity quantum electrodynamics is a rapidly advancing field, which explores the frontiers of light-matter coupling. Metal-based approaches are of particular interest in this field, as they carry the potential to squeeze optical modes to spaces significantly below the diffraction limit. Transition metal dichalcogenides are ideally suited as the active material in cavity quantum electrodynamics, as they interact strongly with light at the ultimate monolayer limit. Here, we implement a Tamm-plasmon-polariton structure and study the coupling to a monolayer of WSe\(_{2}\), hosting highly stable excitons. Exciton-polariton formation at room temperature is manifested in the characteristic energy-momentum dispersion relation studied in photoluminescence, featuring an anti-crossing between the exciton and photon modes with a Rabi-splitting of 23.5 meV. Creating polaritonic quasiparticles in monolithic, compact architectures with atomic monolayers under ambient conditions is a crucial step towards the exploration of nonlinearities, macroscopic coherence and advanced spinor physics with novel, low-mass bosons.},
  language  = {en}
}
@article{HobbsJaskaniecMcCarthyetal.2018,
  author    = {Hobbs, Christopher and Jaskaniec, Sonia and McCarthy, Eoin K. and Downing, Clive and Opelt, Konrad and G{\"u}th, Konrad and Shmeliov, Aleksey and Mourad, Maurice C. D. and Mandel, Karl and Nicolosi, Valeria},
  title     = {Structural transformation of layered double hydroxides: an in situ TEM analysis},
  series = {npj 2D Materials and Applications},
  volume    = {2},
  journal   = {npj 2D Materials and Applications},
  doi       = {10.1038/s41699-018-0048-4},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-320752},
  year      = {2018},
  abstract  = {A comprehensive nanoscale understanding of layered double hydroxide (LDH) thermal evolution is critical for their current and future applications as catalysts, flame retardants and oxygen evolution performers. In this report, we applied in situ transmission electron microscopy (TEM) to extensively characterise the thermal progressions of nickel-iron containing (Ni-Fe) LDH nanomaterials. The combinative approach of TEM and selected area electron diffraction (SAED) yielded both a morphological and crystallographic understanding of such processes. As the Ni-Fe LDH nanomaterials are heated in situ, an amorphization occurred at 250 °C, followed by a transition to a heterogeneous structure of NiO particles embedded throughout a NiFe2O4 matrix at 850 °C, confirmed by high-resolution TEM and scanning TEM. Further electron microscopy characterisation methodologies of energy-filtered TEM were utilised to directly observe these mechanistic behaviours in real time, showing an evolution and nucleation to an array of spherical NiO nanoparticles on the platelet surfaces. The versatility of this characterisation approach was verified by the analogous behaviours of Ni-Fe LDH materials heated ex situ as well as parallel in situ TEM and SAED comparisons to that of an akin magnesium-aluminium containing (Mg-Al) LDH structure. The in situ TEM work hereby discussed allows for a state-of-the-art understanding of the Ni-Fe material thermal evolution. This is an important first, which reveals pivotal information, especially when considering LDH applications as catalysts and flame retardants.},
  language  = {en}
}