arXiv subjects

Hideyuki Kawasoko

Publications and source records attributed to Hideyuki Kawasoko.

3 recordsLinked to original sources

arXiv2021

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

Metallic anti-ThCr$_2$Si$_2$-type $RE_2$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.

cond-mat.mtrl-sci↗

arXiv2021

High electrical conduction of Sb square net in anti-ThCr$_2$Si$_2$ type La$_2$O$_2$Sb thin film grown by multilayer solid-phase epitaxy

Anti-ThCr$_2$Si$_2$ type $RE_2$O$_2$Sb ($RE$ = rare earth) with Sb square net has shown insulating conduction so far. Here we report the synthesis of La$_2$O$_2$Sb epitaxial thin films for the first time by multilayer solid-phase epitaxy. The valence state of Sb was about -2 evaluated from X-ray photoemission spectroscopy measurement, and the indirect band gap of 0.17 eV was observed. The La$_2$O$_2$Sb epitaxial thin film showed unexpectedly high electrical conduction as a narrow gap semiconductor, whose resistivity at room temperature was approximately ten-thousand-fold lower than that of La$_2$O$_2$Sb bulk polycrystal, attributed to increased carrier mobility probably due to suppressed Sb dimerization.

cond-mat.mtrl-sci↗

arXiv2020

Tetragonality induced superconductivity in anti-ThCr$_2$Si$_2$-type $RE_2$O$_2$Bi ($RE$ = rare earth) with Bi square net

We report a series of layered superconductors, anti-ThCr$_2$Si$_2$-type $RE_2$O$_2$Bi ($RE$ = rare earth), composed of electrically conductive Bi square nets and magnetic insulating $RE_2$O$_2$ layers. The superconductivity was induced by separating Bi square nets as a result of excess oxygen incorporation, irrespective of the presence of magnetic ordering in $RE_2$O$_2$ layers. Intriguingly, the transition temperature of all $RE_2$O$_2$Bi including nonmagnetic Y$_2$O$_2$Bi was approximately scaled by the unit cell tetragonality ($c$/$a$), implying a key role of relative separation of the Bi square nets to induce the superconductivity.

cond-mat.supr-con↗