Increased hole mobility in anti-ThCr${}_2$Si${}_2$-type La${}_2$O${}_2$Bi co-sintered with alkaline earth metal oxides for oxygen intercalation and hole carrier doping

Abstract

Metallic anti-ThCr${}_2$Si${}_2$-type $R{E}_2$O${}_2$Bi ($RE$ = rare earth) with Bi square nets show superconductivity while insulating La${}_2$O${}_2$Bi shows high hole mobility, by expanding the c-axis length through oxygen intercalation. In this study, alkaline earth metal oxides (CaO, SrO, and BaO) were co-sintered with La${}_2$O${}_2$Bi. CaO and BaO served as oxygen intercalants without incorporation of Ca and Ba in La${}_2$O${}_2$Bi. On the other hand, SrO served as not only oxygen intercalant but also hole dopant via Sr substitution with La in La${}_2$O${}_2$Bi. The oxygen intercalation and hole doping resulted in expansion of the c-axis length, contributing to improved electrical conduction. In addition, the hole mobility was enhanced up to 150 cm${}^2$V${}^{-1}$s${}^{-1}$ in La${}_2$O${}_2$Bi, which almost doubles the mobility in previous study.

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