Quantum Spin Liquid in Frustrated One-Dimensional LiCuSbO4.

A quantum magnet, LiCuSbO4, with chains of edge-sharing spin -1/2 CuO5 octahedra is reported. While short-range order is observed for T < 10 K, no zero-field phase transition or spin freezing occurs down to 100 mK. Specific heat indicates a distinct high-field phase near the 12 T saturation field. Neutron scattering shows incommensurate spin correlations with q = (0.47 ± 0.01)7&pgr;/a and places an upper limit of 70&mgr;eV on any spin gap. Exact diagonalization of 16-spin easy-plane spin -1/2 chains with competing ferro- and antiferromagnetic interactions (J1 = -- 75 K, J2 = 34 K) accounts for the T > 2 K data. [ABSTRACT FROM AUTHOR]