Coupled dimerized alternating-bond quantum spin chains in the distorted honeycomb-lattice magnet CuSbO

Piyakulworawat, C.*; Morita, Katsuhiro*; Fukumoto, Yoshiyuki*; Hsieh, W.-Y.*; Chen, W.-T.*; Nakajima, Kenji   ; Kawamura, Seiko   ; Zhao, Y.*; Wannapaiboon, S.*; Piyawongwatthana, P.; Sato, Taku*; Matan, K.*

We analyze powder-averaged inelastic neutron scattering and magnetization data for the distorted honeycomb compound CuSbO using a first-order dimer expansion calculation and quantum Monte Carlo simulations. We show that, in contrast to the previously proposed honeycomb lattice model, CuSbO accommodates interacting dimerized spin chains with alternating ferromagnetic-antiferromagnetic couplings along the chain. Moreover, unlike the typical couplings observed in other Cu-based distorted honeycomb magnets, the spin chains in CuSbO primarily couple through an antiferromagnetic coupling that arises between the honeycomb layers, rather than the expected interchain coupling in the layers. This finding reveals a different magnetic coupling scheme for CuSbO. In addition, utilizing X-ray spectroscopy and transmission electron microscopy, we also refine the crystal structure and stacking-fault model of the compound.