Electrical Conductivity through a Single Atomic Step Measured with the Proximity-Induced Superconducting Pair Correlation

Howon Kim, Shi-Zeng Lin, Matthias J. Graf, Yoshinori Miyata, Yuki Nagai, Takeo Kato, Yukio Hasegawa
2016 Physical Review Letters  
Electrical conductivity through a single atomic step measured with the proximity-induced superconducting pair correlation Abstract: Local disordered nanostructures in an atomically thick metallic layer on a semiconducting substrate play significant and decisive roles in transport properties of two-dimensional (2D) conductive systems. We measured the electrical conductivity through a step of monoatomic height in a truly microscopic manner by using as signal the superconducting pair correlation
more » ... pair correlation induced by the proximity effect. The transport property across a step of a one-monolayer Pb surface metallic phase, formed on a Si(111) substrate, was evaluated by inducing the pair correlation around the local defect and measuring its response, i.e. the reduced density of states at the Fermi energy using scanning tunneling microscopy. We found that the step resistance has a significant contribution to the total resistance on a nominally flat surface. Our study also revealed that steps in the 2D metallic layer terminate the propagation of the pair correlation. They enhance superconductivity between the first surface step and the superconductor / normal metal interface by reflectionless tunneling when the step is located within a coherence length. 2 PACS: 73.25.+i, 74.45.+c, 68.37.Ef
doi:10.1103/physrevlett.117.116802 pmid:27661710 fatcat:chedw23ilrcgbf53hzyrdotwry