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Symmetry breaking of in-plane anisotropic magnetoresistance with temperature in La-doped Sr2IrO4 films

Authors :
Hongxia Xue
Rui-Fen Dou
Lin He
Jianchao Meng
Zitao Zhang
Mingrui Liu
Weimin Jiang
Jia-Cai Nie
R. P. Bai
Jingzhuo Ling
Changmin Xiong
Source :
Physical Review B. 100
Publication Year :
2019
Publisher :
American Physical Society (APS), 2019.

Abstract

Electron-doped $\mathrm{S}{\mathrm{r}}_{2}\mathrm{Ir}{\mathrm{O}}_{4}$ has been the subject of much recent attention because of its similarities with hole-doped $\mathrm{L}{\mathrm{a}}_{2}\mathrm{Cu}{\mathrm{O}}_{4}$. However, direct evidence of its superconductivity has not yet been observed, which has led to various unresolved issues related to this material. In this study, a 14-nm-thick La-doped $\mathrm{S}{\mathrm{r}}_{2}\mathrm{Ir}{\mathrm{O}}_{4}$ film was grown on a (001) $\mathrm{SrTi}{\mathrm{O}}_{3}$ substrate. We found that the fourfold component of the in-plane anisotropic magnetoresistance disappears and is replaced by a twofold symmetry as the temperature increases. Variable-temperature x-ray diffraction and spatially resolved optical second-harmonic generation experiments eliminate the possibility of crystal structural distortion. The temperature dependence of direct current magnetization measurements indicates that a change in the spin structure may account for the symmetry breaking, similar to the nematic ordering of iron-based and other superconductors. Remarkably, the transition temperature of the symmetry breaking is well consistent with the previously reported onset (50 K) of the low-energy gap in K-doped $\mathrm{S}{\mathrm{r}}_{2}\mathrm{Ir}{\mathrm{O}}_{4}$ observed by scanning tunneling spectroscopy. Our results provide a perspective on these materials that helps elucidate the nature of magnetic interactions and explores the expected superconductivity of iridates.

Details

ISSN :
24699969 and 24699950
Volume :
100
Database :
OpenAIRE
Journal :
Physical Review B
Accession number :
edsair.doi...........f40b03e616ed94d6ac6b17e35e351120