Synthese, Kristallzucht und physikalische Eigenschaften der Remeika Phasen
Zusammenfassung der Projektergebnisse
As planned, we successfully synthesized all compounds and grew crystals of the mentioned stannides large enough for physical properties measurements. Further attempts to correctly determine the crystal structures of the Remeika phases showed them to be much more complicated than expected and planned high-resolution synchrotron powder XRD is not enough to solve this problem. Therefore, additional TEM investigations as well as chemical bonding analyses were applied in the cases of Y3Rh4Ge13, Y3Ir4Ge13, Yb3Co4Ge13 and Sc5Rh6Sn18. All this allowed us to confirm the superstructures for the first two germanides, the 3D+3 modulation in the Yb-Co compound as well as the strongest structural disorder in the here reported stannides. The determination of crystal structures of Y5Rh6Sn18 and Y3Ir4Sn13 is still in progress. Obviously, TEM studies will be needed for these compounds as well. All compounds listed except Sc3Ir4Si13 and Yb3Co4Ge13 are superconductors (SC) with Tc ≤ 5 K. However, despite the cage-like structural arrangements (is reflected in the complicated phonon spectra and thus, failure of the classical Debye approach in the description of the phononic contribution to specific heat) and frequently non-centrosymmetric crystal structures, they reveal conventional- or strongly coupled BCS-like superconductivity. Although time reversal symmetry breaking was recently reported for Sc5Rh6Sn18 and Y5Rh6Sn18, our combined thermodynamic and muon spin rotation spectroscopy (μSR) studies confirmed unambiguously an s-wave-like energy gap without any nodes for these stannides. And again, to understand the nature of superconductivity in Sc 5Rh6Sn18, additional and within this project not planned temperature dependent Hall effect measurements had to be performed. To investigate the valence fluctuations (VF) in Yb3Co4Ge13 a combined x-ray absorption spectroscopy, magnetic susceptibility and thermodynamic properties measurements study was needed. VF in the germanide reveal a complicated character and cannot be described within the conventional Kondo model. Obviously, this is due to the 3D+3 modulation of the crystal structure. To understand the possible crystal electric field (CEF) influence on VF in the modulated Yb3Co4Ge13 we are now performing additional analysis of the available literature.
Projektbezogene Publikationen (Auswahl)
- Two-gap superconductivity in Ag1-xMo6S8 Chevrel phase. In: Journal of Physics: Condensed Matter, Volume 29 (2017), Number 49
Manuel Feig, Matej Bobnar, Igor Veremchuk, Christoph Hennig, Ulrich Burkhardt, Ronald Starke, Bohdan Kundys, Andreas Leithe-Jasper and Roman Gumeniuk
(Siehe online unter https://doi.org/10.1088/1361-648X/aa97fd) - Superconductivity and magnetism in noncentrosymmetric LaPtGe3 and CePtGe3. In: Physical Review B, Volume 98 (2018), 184516
Manuel Feig, Michael Nicklas, Matej Bobnar, Walter Schnelle, Ulrich Schwarz, Andreas Leithe-Jasper, Christoph Hennig and Roman Gumeniuk
(Siehe online unter https://doi.org/10.1103/PhysRevB.98.184516) - Crystal structure and superconducting properties of Sc5Ir6Sn18. In: Journal of Physics: Condensed Matter, Volume 31 (2019), Number 44
Volodymyr Levytskyi, Manuel Feig, Lev Akselrud, Walter Schnelle, Andreas Leithe-Jasper, Vadim Dyadkin, Dmitry Chernyshov, and Roman Gumeniuk
(Siehe online unter https://doi.org/10.1088/1361-648X/ab32d0) - Conventional isotropic s-wave superconductivity with strong electron-phonon coupling in Sc5Rh6Sn18. In: Physical Review B, Volume 102 (2020), 024508
Manuel Feig, Walter Schnelle, Alexander Maisuradze, Alfred Amon, Christopher Baines, Michael Nicklas, Silvia Seiro, Ludovic Howald, Rustem Khasanov, Andreas Leithe-Jasper and Roman Gumeniuk
(Siehe online unter https://doi.org/10.1103/PhysRevB.102.024508) - Crystal structure, chemical bonding, and electrical and thermal transport in Sc5Rh6Sn18. In: Dalton Transactions, Volume 49 (2020), 6832 - 6841
Manuel Feig, Lev Akselrud, Walter Schnelle, Vadim Dyadkin, Dmitry Chernyshov, Alim Ormeci, Paul Simon, Andreas Leithe-Jasper and Roman Gumeniuk
(Siehe online unter https://doi.org/10.1039/D0DT00324G)
