Mapping Dynamical Magnetic Responses of Ultrathin Micron-Size Superconducting Films Using Nitrogen-Vacancy Centers in Diamond
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2019-07-26 |
| Journal | Nano Letters |
| Authors | Ying Xu, Yijun Yu, Yuen Yung Hui, Yudan Su, Jun Cheng |
| Institutions | State Key Laboratory of Surface Physics, University of California, Berkeley |
| Citations | 22 |
Abstract
Section titled āAbstractāTwo-dimensional superconductors have attracted growing interest because of their scientific novelty, structural tunability, and useful properties. Studies of their magnetic responses, however, are often hampered by difficulties to grow large-size samples of high quality and uniformity. We report here an imaging method that employed NV<sup>-</sup> centers in diamond as a sensor capable of mapping out the microwave magnetic field distribution on an ultrathin superconducting film of micron size. Measurements on a 33 nm thick film and a 125 nm thick bulklike film of Bi<sub>2</sub>Sr<sub>2</sub>CaCu<sub>2</sub>O<sub>8+Ī“</sub> revealed that the alternating current (ac) Meissner effect (or repulsion of ac magnetic field) set in at 78 and 91 K, respectively; the latter was the superconducting transition temperature of both films. The unusual ac magnetic response of the thin film presumably was due to thermally excited vortex-antivortex diffusive motion in the film. Spatial resolution of our ac magnetometer was limited by optical diffraction and the noise level was at 14 Ī¼T/Hz<sup>1/2</sup>. The technique could be extended with better detection sensitivity to extract local ac conductivity/susceptibility of ultrathin or monolayer superconducting samples as well as ac magnetic responses of other two-dimensional exotic thin films of limited lateral size.