Possible Mott transition in layered Sr2Mn3As2O2ﾠsingle crystals
Carr, Scott V.
Harriger, Leland W.
Nevidomskyy, Andriy H.
Single crystals of Sr2Mn3As2O2 have been grown for the first time, for which we show a possible layer-selective Mott insulator behavior. This compound stands out as a hybrid structure of MnO2 and MnAs layers, analogously to the active CuO2 and FeAs layers, respectively, in the cuprate and iron-based high-temperature superconductors. Electrical transport, neutron diffraction measurements, together with density functional theory calculations on Sr2Mn3As2O2 single crystals converge toward a picture of independent magnetic order at T1∼79 K and T2∼360 K for the two Mn sublattices, with insulating behavior at odds with the metallic behavior predicted by calculations. Furthermore, our inelastic neutron-scattering studies of spin-wave dispersions for the Mn(1) sublattice reveal an effective magnetic exchange coupling of SJ∼3.7 meV. This is much smaller than those for the Mn(2) sublattice.