The Diamond Superconducting Quantum Interference Device

Abstract

Diamond is an electrical insulator in its natural form. However, when doped with boron above a critical level (∼0.25 atom %) it can be rendered superconducting at low temperatures with high critical fields. Here we present the realization of a micrometer-scale superconducting quantum interference device (μ-SQUID) made from nanocrystalline boron-doped diamond (BDD) films. Our results demonstrate that μ-SQUIDs made from superconducting diamond can be operated in magnetic fields as large as 4 T independent of the field direction. This is a decisive step toward the detection of quantum motion in a diamond-based nanomechanical oscillator.

Superconducting nano-mechanical diamond resonators

“…At higher magnetic fields, the superconducting transition is shifted to lower input powers and to lower temperatures and a residual resistance appears which can be associated to the increase of quasiparticles in the superconductor. We obtained a superconducting transition temperature of approximately 2.5 K at zero magnetic field in agreement with measurements on non-suspended diamond samples 27,30,31 . We now turn to the mechanical properties of the diamond nano-mechanical resonator.…”

A scanning superconducting quantum interference device with single electron spin sensitivity

“…2a (all measurements reported in this paper are obtained at 4.2 K). The Nb SOT shows pronounced critical current I c oscillations up to exceptionally high field 13,14 of over 1 T (Fig. 2c) with a period corresponding to an effective loop diameter of 238 nm.…”

Sample Preparation for Inorganic Trace Element Analysis

“…However, their large kinetic inductances lead to large flux noise (∼ 100 µΦ 0 / √ Hz). More promising is the use of materials with larger upper critical fields, such as boron-doped diamond 90 . Micrometric SQUIDs based on 100 nm-wide constrictions in 300 nm thick films were demonstrated to operate up to impressive fields of 4 T applied along any direction.…”