Toward the use of NanoSQUIDs to measure the displacement of an NEMS resonator

We discuss steps toward the readout of the position of a nanoelectromagnetic system (NEMS) beam resonator using a Nb nanosuperconducting quantum interference device (nanoSQUID). We describe our fabrication procedure for coupling the nanoSQUID and a suspended Al-coated Si3N4 NEMS resonator together by a combination of focused ion beam lithography and nanomanipulation. We discuss typical electrical characteristics of the integrated devices, and independent postfabrication atomic force microscope nanoindentation measurements of the elastic properties of the integrated resonator to estimate its natural frequencies of vibration. We compare and discuss the response of a nanoSQUID with current-carrying and superconducting screening (noncurrent carrying) modes of operation of the resonator.This work was supported in part by the U.K. National Measurement System Programme, in part by the European Metrology Research Programme project “MetNEMS,” in part by the U.K. Engineering and Physical Sciences Research Council, and in part by the U.K. National Institute for Health Research