Fabrication and characterization of large arrays of mesoscopic gold rings on large-aspect-ratio cantilevers

TL;DR

This paper reports the fabrication of large arrays of mesoscopic gold rings on ultra-sensitive, high-aspect-ratio cantilevers designed for measuring persistent currents under small magnetic fields, combining advanced lithography and material processing.

Contribution

It introduces a novel fabrication method for large mesoscopic gold ring arrays on high-aspect-ratio cantilevers for persistent current measurements.

Findings

Successful fabrication of arrays with up to 10^5 rings

Characterization of cantilever mechanical properties

Design considerations for measuring persistent currents

Abstract

We have fabricated large arrays of mesoscopic metal rings on ultrasensitive cantilevers. The arrays are defined by electron beam lithography and contain up to $10^5$ rings. The rings have a circumference of 1 $\mu$m, and are made of ultrapure (6N) Au that is deposited onto a silicon-on-insulator wafer without an adhesion layer. Subsequent processing of the SOI wafer results in each array being supported at the end of a free-standing cantilever. To accommodate the large arrays while maintaining a low spring constant, the cantilevers are nearly 1 mm in both lateral dimensions and 100 nm thick. The extreme aspect ratio of the cantilevers, the large array size, and the absence of a sticking layer are intended to enable measurements of the rings' average persistent current $\langle I \rangle$ in the presence of relatively small magnetic fields. We describe the motivation for these measurements, the fabrication of the devices, and the characterization of the cantilevers' mechanical properties. We also discuss the devices' expected performance in measurements of $\langle I \rangle$.