Muon spin relaxation study of Halden like spin chains in Layered Li3Cu2SbO6

A large variety of exotic magnetic structure and relevant magnetic properties is observed in honeycomb layered oxides. Recently Koo et al. have observed two magnetic contributions, quasi-free spins at low-temperature and a spin-gapped in Li3Cu2SbO6. Static magnetic susceptibility and ESR data suggest ferromagnetic-antiferromagnetic alternating chains with JFM = -285 K and JAFM = 160 K with a significant amount of Li-defects in the chain. There are about 0.8 quasi-free spins S = ½ per formula unit which cannot be explained by Cu2+ions residing on Li position. Our neutron diffraction study on WISH (RB 1868023) did not reveal any sign of long-range magnetic order down to 50 mK, while inelastic neutron scattering experiments on MERLIN (RB 1890356) shows gaped magnetic excitation around 8 meV. Considering the importance of the Haldane gap, we propose to investigate Li3Cu2SbO6 using MuSR.