SQUID magnetometer based on Grooved Dayem nanobridges and a flux transformer

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.

4 pages, 4 figures