title: Magnetic Orderings in Li2Cu(WO4)2 with Tungstate-Bridged Quasi-1D Spin-1/2 Chains.
abstract: By both experimental measurements and theoretical calculations, we investigated the magnetic and electronic properties of Li2Cu(WO4)2 as a tungstate-bridged quasi-one-dimensional (1D) copper spin-(1/2) chain system. Interestingly, magnetic susceptibility χ(T) and specific heat measurements show that the system undergoes a three-dimensional antiferromagnetic (AF)-like ordering at TN ≈ 3.7 K, below a broad χ(T) maximum at ∼8.9 K indicating a low-dimensional short-range AF spin correlation. Bonner-Fisher model fitting of χ(T) leads to an AF intrachain exchange constant of J/kB = 15.8 ± 0.1 K, and mean-field theory estimation gives an interchain coupling constant of J⊥/kB = 1.6 K, which supports the quasi-1D nature of this spin system. Theoretical evaluation of exchange coupling constants within the generalized gradient approximation (GGA) plus on-site Coulomb interaction (U) shows that the dominant AF exchange interaction is of ∼13.9 K along the a-axis with weak interchain coupling, in agreement with the experimental result of a quasi-1D spin-(1/2) chain system. The GGA+U calculations also predict that Li2Cu(WO4)2 is a charge transfer-type AF semiconductor with a direct band gap of 1.5 eV.
authors: ‡Institute of Physics, Academia Sinica, Taipei 11529, Taiwan.
authors: I Panneer
authors: IP
authors: Muthuselvam
authors: Raman
authors: R
authors: Sankar
authors: ¶Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.
authors: Viveka Nand
authors: VN
authors: Singh
authors: G Narsinga
authors: GN
authors: Rao
authors: ‡Institute of Physics, Academia Sinica, Taipei 11529, Taiwan.
authors: Wei-Li
authors: WL
authors: Lee
authors: Guang-Yu
authors: GY
authors: Guo
authors: ∥National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan.|⊥Ministry of Science and Technology, Taiwan Consortium of Emergent Crystalline Materials, Taipei 10622, Taiwan.
authors: Fang-Cheng
authors: FC
authors: Chou