Bick, M.Schubert, J.Fardmanesh, M.Panaitov, G.Banzet, M.Zander, W.Zhang, Y.Krause, H. J.2015-07-282015-07-282001-031051-8223http://hdl.handle.net/11693/10941he suppression of the critical current in YBCO Josephson junctions by the Earth's magnetic field strongly affects the operation of SQUIDs outside magnetic shielding. Commonly, one observes a modulation of the SQUID fluxvoltage transfer function amplitude, Vsq.pp, with a period of AB,, leading to an increased white flux noise level or unstable SQUID operation. Here, we report on the investigation of AB,., of rf-SQUID sensors based on step edge junctions (SEJ) operated in a flip chip configuration with coplanar resonators with integrated flux concentrators. To investigate the origin of the suppression of Vsq-pp, we opened the SQUID loop of some samples and measured the magnetic field dependence of the critical current I,(B) directly and compared it to VSqJB). It is shown that a junction width in the submicrometer scale is required for operation of the sensors in the Earth's magnetic field.EnglishMagnetic Field DependenceRf-squidSejArticle10.1109/77.919598