Regensburg 2025 – scientific programme
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MA: Fachverband Magnetismus
MA 2: Multiferroics and Magnetoelectric Coupling (joint session MA/KFM)
MA 2.7: Talk
Monday, March 17, 2025, 11:15–11:30, H16
Internal fields at the V-sites and magnetic structure of the lacunar spinel GeV4S8 — •Thomas Gimpel1, Norbert Büttgen1, Hiroyuki Nakamura2, Vladimir Tsurkan1, and István Kézsmárki1 — 1University of Augsburg — 2Graduate School of Engineering, Kyoto
GeV4S8 is a multiferroic lacunar spinel that undergoes both structural (TJT=30 K) and magnetic (TN=13 K) transitions upon which the four V-sites of the V4 tetrahedra that are equivalent in the cubic phase transform into three distinct sets of V-sites with zero-field 51V NMR frequencies of 21.7, 53.6 and 65.6 MHz. This indicates that only two V-sites have the same internal magnetic field, while the other two have different ones. Based on the angular dependence of the resonance field upon the rotation of the field, we conclude that the direction of the internal field is common for the four V-sites and is parallel to one of the cubic [110]-type axes, which indicates that the magnetic space group is Pmn21.
Keywords: NMR; lacunar spinel; multiferroic; magnetic structure