Abstract
The electronic properties of cuprate high-temperature superconductors in their normal state are highly two-dimensional: transport along the crystal planes is perfectly metallic, but is insulating along the perpendicular ‘c-axis’ direction. The ratio of the in-plane to the perpendicular resistance can exceed 10 4 (refs 1–4 ). This anisotropy was identified as one of the mysteries of the cuprates early on 5,6 , and although widely different proposals exist for its microscopic origin 7–9 , there is little empirical information on the microscopic scale. Here, we elucidate the properties of the insulating layers with a newly developed scanning noise spectroscopy technique that can spatially map the current and its time-resolved fluctuations. We discover atomic-scale noise centres that exhibit megahertz current fluctuations 40 times the expectation from Poissonian noise, more than what has been observed in mesoscopic systems 10 . Such behaviour can happen only in highly polarizable insulators and represents strong evidence for trapping of charge in the charge reservoir layers. Our measurements suggest a picture of metallic layers separated by polarizable insulators within a three-dimensional superconducting state.
Original language | English |
---|---|
Pages (from-to) | 1183-1187 |
Number of pages | 5 |
Journal | Nature Physics |
Volume | 14 |
Issue number | 12 |
DOIs | |
Publication status | Published - 2018 Dec 1 |
Bibliographical note
Publisher Copyright:© 2018, The Author(s), under exclusive licence to Springer Nature Limited.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)