Abrikosov vortex memory with improved sensitivity and reduced write current levels

Studies are carried out on a nondstructive readout random access memory cell based on the use of Abrikosov vortices in thin-film type-II superconductor with a view to achieve high vortex sensitivity and low current levels. Employing an overhang structure, the magnetic flux of stored vortices is effectively guided to the sense gate (SG) and the saturated shift value is increased several times larger than that of a cell without an overhang structure. It is also experimentally verified that stored vortices accumulate near the entrance edge of vortex storage region (VSR) because of its large pinning force. Utilizing vortex driving current flowing through VSR film, the vortices are driven toward the SG and accumulated in the VSR near the SG. Low write current levels of less than 6 mA are achieved utilizing low pinning force films, such as amorphous Mo films, using a vortex driving current.