Spin Sensitivity and Magnetic Response Analysis of Nano-SQUIDs

Zejun Shi, Huachuan Wang, Jianxin Lin

Abstract: This paper presents the spin sensitivity and magnetic response analysis of the nano-superconducting-quantum-interference devices (SQUIDs). We employed the computational study to understand the schemes of a nano-SQUID’s detection capability according to the device’s geometry and fabrication process. We find that the performance of the nano-device increased by decreasing the loop size of the SQUIDs, and it reached the maximum value at the corners of the loop. We then estimated the flux noise SΦ of the SQUIDs in the thermal white noise regime and discussed the field amplification factor around the cross-section area. Furthermore, we fabricated YBa2Cu3O7 (YBCO) based nano-SQUIDs with Josephson junctions at MgO biocrystal grain boundaries using the Pulsed Laser Deposition (PLD) and Focused Ion Beam (FIB) technique. By comparison with the estimated value of our calculation, the spin sensitivity evaluated by the experimentally fabricated devices coincides nicely with our estimation.