Doping- and pressure-induced change of electrical and magnetic properties in the Fe-based spin-ladder compound BaFe2 Se3

We have investigated the evolution of electronic structure in the Fe-based ladder compound Ba(Fe1-xCox)2Se3 (0≤x≤0.15) by means of resistivity, magnetic susceptibility, and reflectivity measurements. Although the Co substitution into BaFe2Se3 greatly decreases the resistivity, the compound still shows an insulating behavior at x=0.15. Moreover, the insulating state at x=0.15 is robust even under the high pressure of 8 GPa. The antiferromagnetic transition temperatures are gradually suppressed by substituting Co atoms at x≤0.10, while the spin glass state is observed at x≥0.125. Our finding revealed that the substituted Co atoms play a dual effect: electron-carrier dopant and localized moment, providing a supplemental insight into the doping effect in the Fe-based superconductors.