Correlations, spin dynamics, defects: the highly frustrated kagome bilayer
Correlations, spin dynamics, defects: the highly frustrated kagome bilayer
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DOI：
10.1063/1.2008131
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发表时间：
2005-08-01
影响因子：
0.8
通讯作者：
Blanchard, N
中科院分区：
文献类型：
--
作者：
Bono, D;Limot, L;Blanchard, N
化合物SrCr 9 pGa 12 - 9 pO 19和Ba 2Sn 2 ZnGa 10 - 7 pCr 7 pO 22是两种高阻挫磁体，具有准二维的自旋为3/2的铬离子可果美双层结构，具有反铁磁相互作用。利用局域核磁共振和非局域（SQUID）技术测量了它们的磁化率，利用μ子自旋共振测量了它们的低温自旋动力学。与对几何阻挫系统的理论描述一致，可果美双层膜表现出：（i）在远低于居里-外斯温度的温度下，短程自旋-自旋相关，没有常规的长程跃迁发生;（ii）由自旋空位产生的顺磁缺陷对磁化率的居里贡献;（iii）低温自旋涨落，至少低至30 mK，这是动态基态的标志。这些性质指向自旋液体基态，可能是建立在共振价键上，而非受限自旋子作为磁激发。(C)2005年美国物理学会。
The compounds SrCr9pGa12-9pO19 and Ba2Sn2ZnGa10-7pCr7pO22 are two highly frustrated magnets possessing a quasi-two-dimensional kagome 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 kagome 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. (C) 2005 American Institute of Physics.