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Effects of Rashba-spin–orbit coupling on superconducting boron-doped nanocrystalline diamond films: evidence of interfacial triplet superconductivity

DOI: 10.1088/1367-2630/abafe9 DOI Help

Authors: Somnath Bhattacharyya (University of the Witwatersrand; National University of Science and Technology MISiS) , Davie Mtsuko (University of the Witwatersrand) , Christopher Allen (Diamond Light Source) , Christopher Coleman (University of the Witwatersrand)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: New Journal Of Physics , VOL 22

State: Published (Approved)
Published: September 2020
Diamond Proposal Number(s): 18627

Open Access Open Access

Abstract: Among the many remarkable properties of diamond, the ability to superconduct when heavily doped with boron has attracted much interest in the carbon community. When considering the nanocrystalline boron doped system, the reduced dimensionality and confinement effects have led to several intriguing observations most notably, signatures of a mixed superconducting phase. Here we present ultra-high-resolution transmission electron microscopy imaging of the grain boundary and demonstrate how the complex microstructure leads to enhanced carrier correlations. We observe hallmark features of spin–orbit coupling (SOC) manifested as the weak anti-localization effect. The enhanced SOC is believed to result from a combination of inversion symmetry breaking at the grain boundary interfaces along with antisymmetric confinement potential between grains, inducing a Rashba-type SOC. From a pronounced zero bias peak in the differential conductance, we demonstrate signatures of a triplet component believed to result from spin mixing caused by tunneling of singlet Cooper pairs through such Rashba-SOC grain boundary junctions.

Journal Keywords: superconductivity; boron doped diamond; spin–orbit coupling

Subject Areas: Materials, Physics

Diamond Offline Facilities: Electron Physical Sciences Imaging Centre (ePSIC)
Instruments: E02-JEM ARM 300CF