Intrinsic tunneling study of underdoped Bi2Sr2_xLasCuO_6＋δ superconductors

• Published in: 中国物理：英文版 2011, Vol.20 (11), p.469-472
• Main Author: 任建坤 任育峰 田野 于海峰 郑东宁 赵士平 林成天
• Format: Article
• Language: English
• Subjects: Bi2201; 最低温度; 温度依赖; 电子性质; 约瑟夫森结; 超导转变温度; 铜氧化物超导体; 隧道谱
• ISSN: 1674-1056; 2058-3834

We report on a tunneling study of underdoped submicron Bi2Sr2_xLasCuO_6＋δ （La-Bi2201） intrinsic Josephson junctions （IJJs）, whose self-heating is sufficiently suppressed. The tunneling spectra are measured from 4.2 K up to the pseudogap opening temperature of T＊ = 260 K. The gap value found from the spectral peak position is about 35 meV and has a weak temperature dependence both below and above the superconducting transition temperature of Tc = 29 K. Since the superconducting gap should have a value of 10-15 meV, our results indicate that the pseudogap （～35 meV） plays an important role in the underdoped La-Bi2201 intrinsic tunneling spectroscopy down to the lowest temperature of 4.2 K. However, the contribution of the superconducting gap can be separated by normalizing the spectra to the one near and above Tc, which shows that the IJJs can be a useful tool for the study of the electronic properties of the La-Bi2201 cuprate superconductors.