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

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.

References in corpus (2)

• Quantum magnetism and criticality
• Structural distortion and frustrated magnetic interactions in the layered copper oxychloride [CuCl]LaNb(2)O(7)

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