Magnetic Resonance Study of the Spin-1/2 Quantum Magnet BaAg2Cu[VO4]2

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Abstract
<jats:title>Abstract</jats:title> <jats:p>BaAg<jats:sub>2</jats:sub>Cu[VO<jats:sub>4</jats:sub>]<jats:sub>2</jats:sub> contains Cu(II) <jats:italic>S</jats:italic>=1/2 ions on a distorted two-dimensional triangular lattice interconnected via non-magnetic [VO<jats:sub>4</jats:sub>] entities. DFT band structure calculations, quantum Monte-Carlo simulations, and high-field 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 with nearest neighbor exchange couplings of <jats:italic>J</jats:italic> <jats:sup>FM</jats:sup>=−19 K and <jats:italic>J</jats:italic> <jats:sup>AFM</jats:sup>=9.5 K (A. Tsirlin, A. Möller, B. Lorenz, Y. Skourski, H. Rosner, Phys. Rev. B <jats:bold>85</jats:bold> (2012) 014401). Here we report the study of BaAg<jats:sub>2</jats:sub>Cu[VO<jats:sub>4</jats:sub>]<jats:sub>2</jats:sub> by high-field/frequency electron spin resonance (HF-ESR) and nuclear magnetic resonance (NMR) spectroscopies, which probe the local magnetic properties. In the HF-ESR measurements, we observe an anisotropic ESR spectrum typical for the Cu(II) ions and determine the <jats:italic>g</jats:italic>-tensor, <jats:italic>g</jats:italic> <jats:sub>||</jats:sub>=2.38 and <jats:italic>g</jats:italic> <jats:sub>⊥</jats:sub>=2.06. Moreover, we see a substantial change in the spectral shape of the ESR lines at low temperatures indicating the presence of short range magnetic correlations. The analysis of the low-temperature ESR spectra shows that its peculiar structure is due to the development of the anisotropic internal fields corresponding to FM and AFM correlations in the respective Cu spin chains. In the NMR spectra the signals from <jats:sup>51</jats:sup>V nuclei in the two types of chains were identified. The analysis of the temperature evolution of these signals strongly supports the ESR findings on the occurrence of two types of Cu chains. Altogether, the HF-ESR and NMR results confirm theoretical predictions of the superposition of FM and AFM Cu(II) spin-1/2 chains in the studied material.</jats:p>
Autoren
  • Yulia Krupskaya
  • Markus Schäpers
  • Anja UB Wolter
  • Hans-Joachim Grafe
  • Evgeniya Vavilova
  • Angela Möller
  • Bernd Büchner
  • Vladislav Kataev
DOI
10.1515/zpch-2016-0829
eISSN
2196-7156
ISSN
0942-9352
Ausgabe der Veröffentlichung
4
Zeitschrift
Zeitschrift für Physikalische Chemie
Sprache
en
Online publication date
2016
Paginierung
759 - 775
Datum der Veröffentlichung
2017
Status
Published
Herausgeber
Walter de Gruyter GmbH
Herausgeber URL
http://dx.doi.org/10.1515/zpch-2016-0829
Datum der Datenerfassung
2023
Titel
Magnetic Resonance Study of the Spin-1/2 Quantum Magnet BaAg<sub>2</sub>Cu[VO<sub>4</sub>]<sub>2</sub>
Ausgabe der Zeitschrift
231

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