Vector sensor for scanning SQUID microscopy

29th International Symposium on Superconductivity

Dang, Vu The^1,2 ; Toji, Masaki^1 ; Thanh Huy, Ho^1,2 ; Miyajima, Shigeyuki^3 ; Shishido, Hiroaki^1,4 ; Hidaka, Mutsuo^5 ; Hayashi, Masahiko^6 ; Ishida, Takekazu^1,4

Department of Physics and Electronics, Osaka Prefecture University, Sakai

599-8531, Japan^1

University of Sciences, Vietnam National University HCMC, Ho Chi Minh, Viet Nam^2

National Institute of Information and Communications Technology, Kobe

651-2492, Japan^3

Institute for Nanofabrication Research, Osaka Prefecture University, Sakai

599-8531, Japan^4

National Institute of Advanced Industrial Science and Technology, Tsukuba

305-8568, Japan^5

Faculty of Education and Human Studies, Akita University, Akita

010-8502, Japan^6

关键词: Basic characteristics;    Critical current density Jc;    Fundamental characteristics;    High spatial resolution;    Magnetic field vectors;    Multilayer technology;    Scanning SQUID microscope;    Scanning SQUID microscopy;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/871/1/012075/pdf
DOI  :  10.1088/1742-6596/871/1/012075

来源: IOP

【 摘 要 】

We plan to build a novel 3-dimensional (3D) scanning SQUID microscope with high sensitivity and high spatial resolution. In the system, a vector sensor consists of three SQUID sensors and three pick-up coils realized on a single chip. Three pick-up coils are configured in orthogonal with each other to measure the magnetic field vector of X, Y, Z components. We fabricated some SQUID chips with one uniaxial pick-up coil or three vector pick-up coils and carried out fundamental measurements to reveal the basic characteristics. Josephson junctions (JJs) of sensors are designed to have the critical current density Jcof 320 A/cm2, and the critical current Icbecomes 12.5 μA for the 2.2μm × 2.2μm JJ. We carefully positioned the three pickup coils so as to keep them at the same height at the centers of all three X, Y and Z coils. This can be done by arranging them along single line parallel to a sample surface. With the aid of multilayer technology of Nb-based fabrication, we attempted to reduce an inner diameter of the pickup coils to enhance both sensitivity and spatial resolution. The method for improving a spatial resolution of a local magnetic field image is to employ an XYZ piezo-driven scanner for controlling the positions of the pick-up coils. The fundamental characteristics of our SQUID sensors confirmed the proper operation of our SQUID sensors and found a good agreement with our design parameters.