Magnetic mesa-structure array for ensemble detection applications of nuclear spins

Micro/nanofabrication 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, micro/nanomagnetic smart systems and so on. This work reports a prototype of mesa-structure, micromachined by sputtering NiFe alloys on SiO₂ stripes, for potential applications in ensemble detection of nuclear spins. The status of the magnetic field present around the array of NiFe alloys was stimulated by ANSYS analysis. Subsequently, the mesa-structure array design was carried out according to the stimulated results of ANSYS analysis to obtain a strong magnetic gradient with homogeneous magnetic-flux density which was essential to the ensemble detection of nuclear spins. SiO₂ stripes and the final mesa-structure were micromachined by means of micro-electro-mechanical systems technologies. The scanning electron microscope images demonstrated that the NiFe alloys were finely sputtered on SiO₂ stripes with the ellipse-like shape. The final morphology of mesa-structure alloy was impacted by the vacuum degree in the sputtering process.