Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 72: Poster Session: Correlated Electrons
TT 72.67: Poster
Mittwoch, 14. März 2018, 15:00–19:00, Poster B
Superposition of FM and AFM Cu(II) spin-1/2 chains in BaAg2Cu[VO4]2 studied by magnetic resonance spectroscopies — •Y. Krupskaya1, M. Schäpers1, A.U.B. Wolter1, H.-J. Grafe1, E. Vavilova1,2, A. Möller3, B. Büchner1, and V. Kataev1 — 1IFW Dresden, Dresden, Germany — 2Zavoisky Physical-Technical Institute, Kazan, Russia — 3Johannes Gutenberg University Mainz, Mainz, Germany
BaAg2Cu[VO4]2 contains Cu(II) S=1/2 ions in a distorted two-dimensional triangular lattice interconnected via non-magnetic [VO4] entities. The theoretical analysis and the magnetization measurements show that the magnetism of this compound is determined by a superposition of ferromagnetic (FM) and antiferromagnetic (AFM) uniform spin-1/2 chains. In order to probe the local magnetic properties we have performed the study of BaAg2Cu[VO4]2 by High-Field/Frequency Electron Spin Resonance (HF-ESR) and Nuclear Magnetic Resonance (NMR) spectroscopies. In the HF-ESR measurements, we observe an anisotropic ESR spectrum typical for the Cu(II) ions and determine the g-tensor. The detailed analysis shows that the shape of the low-temperature ESR spectrum is defined by the development of the anisotropic internal fields corresponding to FM and AFM correlations in the respective Cu spin chains. The NMR study has identified the signals from 51V nuclei in the two types of chains, which strongly supports the ESR results. Altogether, the HF-ESR and NMR results confirm theoretical predictions of the superposition of FM and AFM Cu(II) spin-1/2 chains in BaAg2Cu[VO4]2.