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Effect of Indium doping on the superconductivity of layered oxychalcogenide La2O2Bi3Ag1-xInxS6

We report on the substitution effect of Indium (In) at the Ag site of layered oxychalcogenide La2O2Bi3Ag1-xInxS6. The Tc decreases with increasing In concentration. A hump in the normal state resistivity at an anomaly temperature (T*) near 180 K was observed for all the samples. The anomaly in the resistivity at T* is indicating the possible occurrence of a charge-density-wave (CDW) transition. The T* does not markedly change by In doping. The x dependence of Seebeck coefficient suggests that carrier concentration does not change by In doping. The EDX analysis indicates small amount of Bi deficiency, which suggests that the Bi site is slightly substituted by In. The CDW transition is robust against the In substitution at Ag site, while Tc is decreasing due to the Bi site substitution by In. On the basis of those analyses, we propose that the suppression of superconductivity in the In-doped La2O2Bi3Ag1-xInxS6 system is caused by negative in-plane chemical pressure effect and partial substitution of In for the in-plane Bi site.