Increased hole mobility in anti-ThCr2Si2-type La2O2Bi co-sintered with alkaline earth metal oxides for oxygen intercalation and hole carrier doping

Abstract

Metallic anti-ThCr₂Si₂-type RE₂O₂Bi (RE = rare earth) with Bi square nets show superconductivity while insulating La₂O₂Bi 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 La₂O₂Bi. CaO and BaO served as oxygen intercalants without the incorporation of Ca and Ba in La₂O₂Bi. On the other hand, SrO served not only as an oxygen intercalant but also as a hole dopant via Sr substitution for La in La₂O₂Bi. The oxygen intercalation and hole doping resulted in the expansion of the c-axis length, contributing to the improved electrical conduction. In addition, the hole mobility was enhanced up to 150 cm² V⁻¹ s⁻¹ in La₂O₂Bi, which is almost double the mobility in a previous study.