Spatially-resolved study of the Meissner effect in superconductors using NV-centers-in-diamond optical magnetometry. (12th April 2018)

• Record Type: Journal Article
• Authors: Nusran, N M; Joshi, K R; Cho, K; Tanatar, M A; Meier, W R; Bud'ko, S L; Canfield, P C; Liu, Y; Lograsso, T A; Prozorov, R
• Is Part Of: New journal of physics. Volume 20:Number 4(2018:Apr.)
• Publication Date: 2018-04-12
• Subjects: NV-centers in diamond -- Meissner effect -- optical magnetometry -- paramagnetic Meissner effect -- anomalous Meissner effect; Physics -- Periodicals; Physics; Periodicals; 530.05
• DOI: 10.1088/1367-2630/aab47c
• Languages: English
• ISSNs: 1367-2630

Abstract

Abstract: Non-invasive magnetic field sensing using optically-detected magnetic resonance of nitrogen-vacancy centers in diamond was used to study spatial distribution of the magnetic induction upon penetration and expulsion of weak magnetic fields in several representative superconductors. Vector magnetic fields were measured on the surface of conventional, elemental Pb and Nb, and compound LuNi2 B2 C and unconventional iron-based superconductors Ba1− x K x Fe2 As2 ( x = 0.34 optimal hole doping), Ba(Fe1− x Co x )2 As2 ( x = 0.07 optimal electron doping), and stoichiometric CaKFe4 As4, using variable-temperature confocal system with diffraction-limited spatial resolution. Magnetic induction profiles across the crystal edges were measured in zero-field-cooled and field-cooled conditions. While all superconductors show nearly perfect screening of magnetic fields applied after cooling to temperatures well below the superconducting transition, T c, a range of very different behaviors was observed for Meissner expulsion upon cooling in static magnetic field from above T c . Substantial conventional Meissner expulsion is found in LuNi2 B2 C, paramagnetic Meissner effect is found in Nb, and virtually no expulsion is observed in iron-based superconductors. In all cases, good correlation with macroscopic measurements of total magnetic moment is found.