Observation of a superconducting glass state in granular superconducting diamond

Abstract

The magnetic field dependence of the superconductivity in nanocrystalline boron doped diamond thin films is reported. Evidence of a superconducting glass state is presented, as demonstrated by the observation of a quasi de Almeida-Thouless line in the phase diagram and a logarithmic time dependence of the magnetism. The position of the phase boundary in the H-T plane is determined from electrical transport data by detailed fitting to quasi-zero-dimensional fluctuation conductivity theory. This allows determination of the boundary between resistive and non-resistive behaviour to be made with greater precision than the standard ad hoc onset/midpoint/offset criterion. We attribute the glassy superconductivity to the morphological granularity of the diamond films.

Single-crystalline boron-doped diamond superconducting quantum interference devices with regrowth-induced step edge structure

“…Thus, the fabrication of a superconducting circuit on an insulating substrate with good adhesion between the substrate and superconductor can be achieved. Moreover, growth of superconducting nanocrystalline diamond 24 on silicon nitride has recently been reported 25 , which opens a path towards the development of new diamond device applications. In addition to the above excellent characteristics, diamond exhibits strong tolerance to oxidation, heating, and physical scratches, and its microfabrication using oxygen plasma etching or selective epitaxial growth is easy 23,26 .…”

Fluctuation spectroscopy in granular superconductors with application to boron-doped nanocrystalline diamond

“…al. [13,14], and proceed to compute these numerically to make comparison to experimental observation. We take T c = 3.8 K, E T h = 1 K (D 0 = 13.1 cm s −1 ), Γ = 2.62 × 10 −2 K, a = 10 −7 m, and δ = 5.6 × 10 −3 K (this corresponds to a carrier concentration of n = 10 27 m −3 ).…”

“…al. [13,14] characterised the granular transport properties in films of boron-doped nanocrystalline diamond (BNCD), where T c 4K. In [13] they measured the corrections to the electrical conductivity due to superconducting fluctuations and observed two crossovers in the behavior of the fluctuation conductivity.…”

Phase Slips and Metastability in Granular Boron-doped Nanocrystalline Diamond Microbridges

“…The general superconducting properties of BNCD (T c ∼ 4 K and ξ ∼ 10 nm) [12] are similar to bulk single crystalline samples [24] but the detailed behavior is modified by the granular microstructure [22,23], which is unusual for a superconducting material in that columnar grains extend vertically through the entire film. Indeed, we have previously seen a 3D-0D-3D dimensional crossover in the fluctuation conductivity arising from the granularity [12,25].…”