28 August 2022 to 2 September 2022
Science and Technology Campus, University of Parma
Europe/Rome timezone
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Muonium states in semiconducting transition metal dichalcogenides

1 Sep 2022, 14:40
20m
Science and Technology Campus, University of Parma

Science and Technology Campus, University of Parma

University of Parma, Italy
Oral Semiconductors Oral contributions

Speaker

Jonas A. Krieger (Max Planck Institute of Microstructure Physics)

Description

The usual response of muonium to an external magnetic field is dominated by the hyperfine interaction, which causes the observed spectrum to show the transition frequencies between different muonium spin states. However, we have recently discovered an unconventional magnetic muonium state in 2H-MoTe$_2$ where the muonium acts a magnetic impurity, which polarizes the local electronic magnetic moments $[1]$. For sufficiently small externally applied fields, the "magnetic" muonium effectively behaves as a diamagnetic muon in a local magnetic field. Here, we show experimentally that in 2H-MoTe$_2$ the magnetic muonium coexists with another conventional, non-magnetic muonium state (Fig. 1b). The latter is axially symmetric with a hyperfine coupling of A$_\parallel$=1426(1) MHz and A$_\perp$=1368(3) MHz, corresponding to an effective Bohr radius of $\approx$ 0.82 Angstrom. The hyperfine coupling remains fairly constant, as a function of temperature, until the state disappears around the same temperature where the magnetic muonium disappears as well. We employ density functional theory calculations to reveal that this is linked to the presence of two muonium sites in the compound: one within the van der Waals gap that becomes magnetic, and a second one inside the layer, that is conventional. A similar behavior is also observed in 2H-WSe$_2$ (Fig. 1a), indicating that this is a more general feature of semiconducting transition metal dichalcogenides.

$[1]$ J. A. Krieger, et al., arXiv:2206.03051 (2022)

(a) Local field distribution in 2H-WSe$_2$ at 5K in a 0.7T transverse field. (b) Applied field dependence of the oscillation frequencies in 2H-MoTe$_2$ at 5.5K.

Primary author

Jonas A. Krieger (Max Planck Institute of Microstructure Physics)

Co-authors

Igor P. Rusinov (Tomsk State University, pr. Lenina 36, 634050 Tomsk, Russia) Dr Zurab Guguchia (Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland) Sourabh Barua (Department of Physics, University of Warwick, Coventry CV4 7AL, UK) Dr Pabitra Biswas (STFC / UKRI) Lukas Korosec (Laboratorium für Festkörperphysik, ETH Zürich, CH-8093 Zürich, Switzerland) Dr Thomas Prokscha (PSI) Dr Robert Scheuermann (Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland) Thorsten Schmitt (Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland) Niels B. M. Schröter (Max Planck Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany) T. Shang (Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University) Dr Toni Shiroka (Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland ) Dr Andreas Suter (PSI) Daniel Tay (Laboratorium für Festkörperphysik, ETH Zürich, CH-8093 Zürich, Switzerland) Prof. Geetha Balakrishnan (Warwick University) Dr Evgueni V. Chulkov (DIPC, Donostia, Spain) Stuart S. P. Parkin (Max Planck Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany) Vladimir N. Strocov (Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland) Zaher Salman (Paul Scherrer Institute)

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