Micron size superconducting quantum interference devices of lead (Pb)

TL;DR

This paper reports the fabrication and characterization of micron-sized lead (Pb) SQUIDs for nano-magnetic probing, demonstrating their superconducting properties and magnetic field response.

Contribution

It introduces a novel fabrication method for Pb-based $$-SQUIDs with small grain size and analyzes their electrical and magnetic characteristics.

Findings

Pb $$-SQUIDs exhibit expected magnetic oscillations.

Devices show hysteresis at low temperatures that disappears near the critical temperature.

Successful fabrication of micron-sized Pb SQUIDs for nano-magnetism applications.

Abstract

Micron size superconducting quantum interference devices ($\mu$-SQUID) of lead (Pb), for probing nano-magnetism, were fabricated and characterized. In order to get continuous Pb films with small grain size, Pb was thermally evaporated on a liquid nitrogen cooled Si substrate. Pb was sandwiched between two thin Cr layers for improved adhesion and protection. The SQUID pattern was made by e-beam lithography with Pb lift-off after deposition. The current-voltage characteristics of these devices show a critical current, which exhibits the expected SQUID oscillations with magnetic field, and two re-trapping currents. As a result these devices have hysteresis at low temperatures, which disappears just below the critical temperature.