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arXiv · 1006.0755

Ferromagnetically coupled Shastry-Sutherland quantum spin singlets in (CuCl)LaNb$_2$O$_7$

C. Tassel·J. Kang·C. Lee·O. Hernandez·Y. Qiu·W. Paulus·E. Collet·B. Lake·T. Guidi·M. -H. Whangbo·C. Ritter·H. Kageyama·S. -H. Lee
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Abstract

Using inelastic neutron scattering, x-ray, neutron diffraction, and the first-principle calculation techniques, we show that the crystal structure of the two-dimensional quantum spin system (CuCl)LaNb$_2$O$_7$ is orthorhombic with $Pbam$ symmetry in which CuCl$_4$O$_2$ octahedra are tilted from their high symmetry positions and the Cu$^{2+} (s = 1/2)$ ions form a distorted square lattice. The dominant magnetic interactions are the fourth nearest neighbor antiferromagnetic interactions with a Cu-Cl--Cl-Cu exchange path, which lead to the formation of spin singlets. The two strongest interactions between the singlets are ferromagnetic, which makes (CuCl)LaNb$_2$O$_7$ the first system of ferromagnetically coupled Shastry-Sutherland quantum spin singlets.

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C. Tassel, J. Kang, C. Lee, O. Hernandez, Y. Qiu, W. Paulus, E. Collet, B. Lake, T. Guidi, M. -H. Whangbo, C. Ritter, H. Kageyama, S. -H. Lee. 2010-06-03. Ferromagnetically coupled Shastry-Sutherland quantum spin singlets in (CuCl)LaNb$_2$O$_7$. https://doi.org/10.1103/physrevlett.105.167205

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