Study on less-than-4-µm period permalloy propagation tracks using a new narrow-gap delineation technique

We have developed a new narrow-gap delineation technique using conventional photolithography, which can decrease the gap size down to 0.2 μm by ion-milling Cu-coated 1-μm-gap photo resist patterns. By applying this narrow gap process to a new bubble propagation structure, less-than-4-μm-period propagation tracks and turns were designed and tested. Good propagation performance in a 3 μm period straight track and 180° turns was obtained at quasi-static operation with three consecutive 1 μm bubbles although no bias margin of consecutive bubbles was obtained in less-than-2.6-μm-period tracks even at the drive field of 80 Oe.