Decoupled Spin Chains in Ba${}_3$CuSb${}_2$O${}_9$

Abstract

Inspired by recent measurements on Ba${}_3$CuSb${}_2$O${}_9$, we explore the interplay of spin and orbital degrees of freedom in a triangular lattice for possible spin liquid-like behaviour. Our effective Hamiltonian describes the magnetic Cu layer by considering superexchange paths along the intermediate O's. A mean field study of ordered states reveals an orbitally ordered ground state that isolates the spin degrees of freedom into spin chains. This scenario naturally explains the linear specific heat as $T\to 0$ and, by including the effects of additional defect Cu's sitting off the triangular planes, we find remarkable agreement with the measured magnetic susceptibility.

4 pages, 3 figures

References in corpus (3)

• High pressure sequence of Ba_3NiSb_2O_9 structural phases: new $S=1$ quantum spin-liquids based on Ni^{2+}
• Frustration and entanglement in the $t_{2g}$ spin--orbital model on a triangular lattice: valence--bond and generalized liquid states
• Frustrated quantum critical theory of putative spin-liquid phenomenology in 6H-B-Ba3NiSb2O9