SQUID magnetometer based on Grooved Dayem nanobridges and a flux transformer

TL;DR

This paper presents a high-sensitivity SQUID magnetometer using Grooved Dayem nanobridges in YBCO, achieving low flux noise and enhanced magnetic field detection at 77 K through a flux transformer with a flip-chip coupling scheme.

Contribution

The study introduces a novel SQUID design with Grooved Dayem nanobridges and a flux transformer, significantly improving magnetic field sensitivity at liquid nitrogen temperatures.

Findings

Flux noise as low as 10 μΦ₀/Hz^{0.5} achieved

Magnetic field noise of 50 fT/Hz^{0.5} at 77 K demonstrated

Enhanced effective area via flip-chip flux transformer coupling

Abstract

We report noise measurements performed on a SQUID magnetometer implementing Grooved Dayem nanobridge of YBCO as weak-links. The SQUID shows magnetic flux noise as low as 10 $\mu \Phi_0$/Hz$^{0.5}$. The magnetometer is realized by coupling the SQUID to a flux transformer with a two-level coupling scheme using a flip-chip approach. This improves the effective area of the SQUID and result in a magnetic field noise of 50 fT/Hz$^{0.5}$ at T=77 K.