Correlations, spin dynamics, defects: the highly-frustrated Kagomé bilayer

• Published in: Физика низких температур
• Date: 2005
• Main Authors: Bono, D., Limot, L., Mendels, P., Collin, G., Blanchard, N.
• Format: Article
• Language: English
• Published: Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України 2005
• Subjects: К семидесятилетию антиферромагнетизма
• Online Access: https://nasplib.isofts.kiev.ua/handle/123456789/121689
• Journal Title: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Cite this: Correlations, spin dynamics, defects: the highly-frustrated Kagomé bilayer / D. Bono, L. Limot, P. Mendels, G. Collin, N. Blanchard // Физика низких температур. — 2005. — Т. 31, № 8-9. — С. 929-951. — Бібліогр.: 92 назв. — англ.

The SrCr₉p Ga₁₂-₉pO₁₉ and Ba₂Sn₂ ZnGa₁₀-₇p Cr₇pO₂₂ compounds are two highly-frustrated magnets possessing a quasi-two-dimensional Kagomé bilayer of spin 3/2 chromium ions with antiferromagnetic interactions. Their magnetic susceptibility was measured by local nuclear magnetic resonance and nonlocal (SQUID) techniques, and their low-temperature spin dynamics by muon spin resonance. Consistent with the theoretical picture drawn for geometrically frustrated systems, the Kagomé 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.