Filters

2018 - 20203

More filters

20203
Reset filters

Settings

Author: Doert, T. × Type: Text ×

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Syntheses, crystal structure and magnetic properties of Tl9RETe6 (RE = Ce, Sm, Gd)
    (Basel : MDPI AG, 2020) Isaeva, A.; Schönemann, R.; Doert, T.
    The three compounds Tl9RETe6 with RE = Ce, Sm, Gd were synthesized from the elements at 1020 K. Their isostructural crystal structures are ordered derivatives of the Tl5Te3 type with rare-earth metal and thallium occupying different Wyckoff positions. The structures can be understood as charge-ordered in accordance with the Zintl-Klemm concept: 9 Tl+ + RE3+ + 6 Te2-. DFT calculations for Tl9GdTe6, however, result in a low, but finite density of states at the Fermi level. Magnetic data confirm trivalent Gd, but indicate a small amount of Ce4+ in Tl9CeTe6; no indications for long-range magnetic order was found down to T = 2 K.
  • Thumbnail Image
    Item
    Pressure-induced dimerization and valence bond crystal formation in the Kitaev-Heisenberg magnet α-RuCl3
    (College Park, MD : American Physical Society, 2018) Bastien, G.; Garbarino, G.; Yadav, R.; Martinez-Casado, F.J.; Beltrán, Rodríguez, R.; Stahl, Q.; Kusch, M.; Limandri, S.P.; Ray, R.; Lampen-Kelley, P.; Mandrus, D.G.; Nagler, S.E.; Roslova, M.; Isaeva, A.; Doert, T.; Hozoi, L.; Wolter, A.U.B.; Büchner, B.; Geck, J.; Van Den Brink, J.
    Magnetization and high-resolution x-ray diffraction measurements of the Kitaev-Heisenberg material α-RuCl3 reveal a pressure-induced crystallographic and magnetic phase transition at a hydrostatic pressure of p∼0.2 GPa. This structural transition into a triclinic phase is characterized by a very strong dimerization of the Ru-Ru bonds, accompanied by a collapse of the magnetic susceptibility. Ab initio quantum-chemistry calculations disclose a pressure-induced enhancement of the direct 4d-4d bonding on particular Ru-Ru links, causing a sharp increase of the antiferromagnetic exchange interactions. These combined experimental and computational data show that the Kitaev spin-liquid phase in α-RuCl3 strongly competes with the crystallization of spin singlets into a valence bond solid.
  • Thumbnail Image
    Item
    Spin-glass state and reversed magnetic anisotropy induced by Cr doping in the Kitaev magnet α-RuCl3
    (College Park, MD : American Physical Society, 2019) Bastien, G.; Roslova, M.; Haghighi, M.H.; Mehlawat, K.; Hunger, J.; Isaeva, A.; Doert, T.; Vojta, M.; Büchner, B.; Wolter, A.U.B.
    Magnetic properties of the substitution series Ru1-xCrxCl3 were investigated to determine the evolution from the anisotropic Kitaev magnet α-RuCl3 with Jeff=1/2 magnetic Ru3+ ions to the isotropic Heisenberg magnet CrCl3 with S=3/2 magnetic Cr3+ ions. Magnetization measurements on single crystals revealed a reversal of the magnetic anisotropy under doping, which we argue to arise from the competition between anisotropic Kitaev and off-diagonal interactions on the Ru-Ru links and approximately isotropic Cr-Ru and isotropic Cr-Cr interactions. In addition, combined magnetization, ac susceptibility, and specific-heat measurements clearly show the destabilization of the long-range magnetic order of α-RuCl3 in favor of a spin-glass state of Ru1-xCrxCl3 for a low doping of x≤0.1. The corresponding freezing temperature as a function of Cr content shows a broad maximum around x ≤ 0.45.