Analysis and design of magnetic mesa-structure array for ensemble detection applications of nuclear spins

Micro/nano fabrication of magnetic materials is becoming a crucial technology for future magnetic systems/devices such as high-density magnetic recording heads, high-density patterned media, magnetic quantum devices, and micro/nano magnetic smart systems, etc. In our previous work, NiFe alloy with the highest saturation magnetic-flux density was selected as the micro-magnet for detecting the feasibility of all-silicon quantum computer. The micro-magnet was designed to create a large magnetic field gradient and to distinguish ²⁹Si nuclear spins arranged as chains in a ²⁸Si matrix with Larmor frequencies. This paper reports the possibility of micro fabrication of a NiFe alloy mesa structure by sputtering NiFe alloy on the top of Si substrate with SiO₂ stripes for potential application of ensemble detection of nuclear spins. The mesa structure array design was carried out based on the results of ANSYS analysis, in the aim to obtain a strong magnetic gradient with homogeneous magnetic-flux density for single micro-magnet, and to reduce mutual cancellation which caused by magnetic field superimposition.