Low-Noise Diamond-Based DC Nano-SQUIDs

Manjith Bose, Daniel L. Creedon, Anders Barlow, Michael Stuiber, Georgina M. Klemencic, Soumen Mandal, Oliver Williams, Grant van Riessen, Christopher I. Pakes

ACS Appl. Electron. Mater. 4, 5, 2246–2252 (2022) https://doi.org/10.1021/acsaelm.2c00048

Nanoscale superconducting quantum interference devices (nano-SQUIDs) with Dayem bridge junctions and a physical loop size of 50 nm have been engineered in boron-doped nanocrystalline diamond films using precision Ne-ion beam milling. In an unshunted device, the nonhysteretic operation can be maintained in an applied field exceeding 0.1 T with a high flux-to-voltage transfer function, giving a low flux noise  at 1 kHz and a concurrent spin sensitivity of . At elevated magnetic fields, up to 2 T, flux modulation of the nano-SQUID output voltage is maintained but with an increase in period, attributed to an additional phase bias induced on the nano-SQUID loop by up to 16 vortices per period penetrating the nano-SQUID electrodes.