Correlations, spin dynamics, defects: the highly-frustrated Kagom\'{e} bilayer

• Published in: arXiv.org 2005-03
• Main Authors: Bono, David, Limot, Laurent, Mendels, Philippe, Gaston, Collin, Blanchard, Nicole
• Format: Article
• Language: English
• Subjects: Antiferromagnetism; Chromium; Curie temperature; Defects; Ground state; Magnetic permeability; Magnetism; Magnets; NMR; Nuclear magnetic resonance; Spin dynamics; Spin resonance; Superconducting quantum interference devices; Trademarks; Variations
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.0503496

The SrCr\(\_{9p}\)Ga\(\_{12-9p}\)O\(\_{19}\) and Ba\(\_{2}\)Sn\(\_{2}\)ZnGa\(\_{10-7p}\)Cr\(\_{7p}\)O\(\_{22}\) compounds are two highly-frustrated magnets possessing a quasi-two-dimensional Kagom\'{e} bilayer of spin 3/2 chromium ions with antiferromagnetic interactions. Their magnetic susceptibility was measured by local Nuclear Magnetic Resonance and non-local (SQUID) techniques, and their low-temperature spin dynamics by Muon Spin Resonance. Consistent with the theoretical picture drawn for geometrically frustrated systems, the Kagom\'{e} bilayer is shown here to exhibit: (i) short range spin-spin correlations down to a temperature much lower than the Curie-Weiss temperature, no conventional long-range transition occurring; (ii) a Curie contribution to the susceptibility from paramagnetic defects generated by spin vacancies; (iii) low-temperature spin fluctuations, at least down to 30 mK, which are a trademark of a dynamical ground state. These properties point to a spin-liquid ground state, possibly built on Resonating Valence Bonds with unconfined spinons as the magnetic excitations.