Dresden 2017 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 68: Poster 5

MA 68.12: Poster

Freitag, 24. März 2017, 09:30–13:00, P2-OG4

NMR of the frustrated spin-ladder system Copper Sulfolane — •D. Dmytriieva^1,2, Z. T. Zhang^1,3, M. Naumann¹, J. Wosnitza^1,2, E. Wulf⁴, A. Zheludev⁴, and H. Kühne¹ — ¹Hochfeld-Magnetlabor Dresden (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany — ²Institut für Festkörperphysik, TU Dresden, Germany — ³Institute of Ion Beam Physics and Materials Research, HZDR, Dresden, Germany — ⁴Neutron Scattering and Magnetism, Laboratory for Solid State Physics, ETH Zuerich, Switzerland

We present results from NMR experiments on the geometrically frustrated quantum magnet Copper Sulfolane. The ground state is a disordered spin liquid that evolves into a chiral helimagnetic phase at fields above about 4 T. NMR of ³⁵Cl nuclei on two nonequivalent sites was performed to map the local susceptibility and charge-gradient tensors close to the Cu²⁺ S = 1/2 moments. The field-driven transition into the helimagnetic state, probed via ¹³C NMR, yields a drastic increase of slow spin fluctuations, manifested as a sharp maximum of the nuclear spin-lattice relaxation rate. Further, we investigated the effect of a dilute and random modification of the local frustration ratio, introduced by Br substitution on the nonmagnetic halogen site. Bulk thermodynamic measurements indicate that surprisingly small Br concentrations have a strong impact on the magnetic correlations of the helimagnetic state. In line with these findings, we observed a strong suppression of the dynamic properties with Br substitution.