Yüksek çözünürlüklü manyetik görüntüleme sistemleri için, rf-SQUID ve SQUID entegrasyon bağlama üretim ve optimizasyon

Superconducting QUantum Interference Devices or SQUIDs are by far themost sensitive devices known for sensing magnetic flux down to a resolution ofabout 10−21 Wb and finds innumerous applications in various fields. In order toapply these sensors to sense nano structures or to use in antibody or antigenammunoassay experiments, especially in unshielded environments at Liquid Ni-trogen temperatures, one needs to optimize the SQUIDs for high SNR and lowbackground magnetic field sensitivity. The chief motivation for this research workand this thesis is to optimize and characterize HTc rf-SQUIDs so that high fieldsensitivity and high spatial resolution could be obtained.During the course of this study, rf-SQUIDs were fabricated using SEJ and Bi-crystal technology and optimized for the above mentioned characteristics. In thenext stage, these optimized sensors were integrated into an imaging system aftera thorough investigation on problems related to the front-end assembly of sucha system. Different SQUID microscope systems have been designed, fabricated,and tested in order to achieve high field sensitivity and high spatial resolutionmagnetic imaging under the constraint of keeping the sample at room tempera-ture, while the SQUID is in Liquid Nitrogen Temperature. Using the developedsystems, magnetic imaging of room temperature samples with sensitivities in√the range of about 100f T / (Hz) and spatial resolution of about 100 µm wereachieved.Keywords: Superconductor, YBCO, Josephson Junction, Step Edge junction,Bicrystal junction, rf-SQUID, Scanning SQUID microscope.iv