Distinction between critical current effects and intrinsic anomalies in the point-contact Andreev reflection spectra of unconventional superconductors
Ge He(何格)1,2, Zhong-Xu Wei(魏忠旭)1,2, Jérémy Brisbois3, Yan-Li Jia(贾艳丽)1,2, Yu-Long Huang(黄裕龙)1,2, Hua-Xue Zhou(周花雪)1,2, Shun-Li Ni(倪顺利)1,2, Alejandro V Silhanek3, Lei Shan(单磊)1,2,4, Bei-Yi Zhu(朱北沂)1, Jie Yuan(袁洁)1, Xiao-Li Dong(董晓莉)1,2,4, Fang Zhou(周放)1,2,4, Zhong-Xian Zhao(赵忠贤)1,2,4, Kui Jin(金魁)1,2,4
1. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;2. School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China;3. Experimental Physics of Nanostructured Materials, Q-MAT, CESAM, Université de Liège, B-4000 Sart Tilman, Belgium;4. Collaborative Innovation Center of Quantum Matter, Beijing 100190, China>
In this work, we discuss the origin of several anomalies present in the point-contact Andreev reflection spectra of (Li1-xFex)OHFeSe, LiTi2O4, and La2-xCexCuO4. While these features are similar to those stemming from intrinsic superconducting properties, such as Andreev reflection, electron-boson coupling, multigap superconductivity, d-wave and p-wave pairing symmetry, they cannot be accounted for by the modified Blonder-Tinkham-Klapwijk (BTK) model, but require to consider critical current effects arising from the junction geometry. Our results point to the importance of tracking the evolution of the dips and peaks in the differential conductance as a function of the bias voltage, in order to correctly deduce the properties of the superconducting state.
Project supported by the National Key Basic Research Program of China (Grant Nos. 2015CB921000, 2016YFA0300301, and 2017YFA0302902), the National Natural Science Foundation of China (Grant Nos. 11674374 and 1474338), the Key Research Program of Frontier Sciences, Chinese Academy of Sciences (Grant No. QYZDB-SSW-SLH008), the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant Nos. XDB07020100 and XDB07030200), the Beijing Municipal Science and Technology Project (Grant No. Z161100002116011), the Fonds de la Recherche Scientifique-FNRS and the ARC Grant 13/18-08 for Concerted Research Actions, financed by the French Community of Belgium (Wallonia-Brussels Federation). Jérémy Brisbois acknowledges the support from F.R.S.-FNRS (Research Fellowship), The work of Alejandro V Silhanek is partially supported by PDR T.0106.16 of the F.R.S.-FNRS.
Ge He, Zhong-Xu Wei, Jérémy Brisbois, Yan-Li Jia, Yu-Long Huang, Hua-Xue Zhou, Shun-Li Ni, Alejandro V Silhanek, Lei Shan, Bei-Yi Zhu, Jie Yuan, Xiao-Li Dong, Fang Zhou, Zhong-Xian Zhao, Kui Jin. Distinction between critical current effects and intrinsic anomalies in the point-contact Andreev reflection spectra of unconventional superconductors[J]. Chin. Phys. B, 2018, 27(4): 047403.