B-site Fe doping effect on the structure and electronic transport properties of quasi-one-dimensional spin ladder compound Sr14(Cu1－yFey)24O41

Abstract

Two groups of Sr14(Cu1-yFey)24O41 compounds with Fe3+ doping and 2/3Fe3++1/3Fe2+ admixture doping respectively were prepared by conventional solid-state reaction. X-ray diffraction analysis shows that the samples have single phase with y≤0.03 of Fe3+ doping and y≤0.02 of 2/3Fe3++1/3Fe2+ admixture doping. The lattice parameters a and b decrease gradually when the doping content increases for each group. The measurements of electronic transport properties show that the electrical resistivity decreases monotonically with the increase in y of Fe3+ doping, which indicates that free hole carriers in the ladder increase. A crossover temperature Tρ was observed in the Arrhenius plot of the resistivity versus temperature. The decrease of resistivity of the Fe3+ doped samples is interpreted in term of the dissociation of spin dimers and hole pairs located in the ladder induced by the substitution of Fe3+ for Cu2+ .Two kinds of possible conduction mechanisms above and below Tρ are presented respectively. The fitting of experimental data proves that the conduction mechanism above Tρ is due to thermal activated single-holes′ contribution, while below Tρ one-dimensional hopping conduction is dominant.