arXiv subjects

Ryosuke Sei

Publications and source records attributed to Ryosuke Sei.

2 recordsLinked to original sources

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↗

arXiv2017

Magnetic and magnetotransport properties of ThCr2Si2-type Ce2O2Bi composed of conducting Bi2- square net and magnetic Ce-O layer

ThCr2Si2-type Ce2O2Bi epitaxial thin films were grown by recently developed multilayer solid phase epitaxy. The ionic state of Ce was confirmed to be 3+ by x-ray photoelectron spectroscopy, corresponding to the electronic configuration of [Xe]4f1. Electrical resistivity showed the nonmonotonic temperature dependence with a sharp resistivity maximum, concomitant with a magnetization kink at 10 K, suggesting antiferromagnetic transition. In addition, magnetoresistance showed a large angular-dependent magnetoresistance. These results imply that carrier transport in the Bi2- square net could be influenced by magnetic ordering in the Ce-O layer owing to its unique layered structure [Bi2-/(Ce2O2)2+], particularly in the form of epitaxial thin films.

cond-mat.mtrl-sci↗