Focused ion beam structured Co/Pt multilayers for field-coupled magnetic computing

Abstract

ABSTRACTWe fabricated and patterned magnetic dots from Co/Pt multilayers and optimized the structure for strong inter-dot magnetic coupling. SQUID measurements show strong perpendicular anisotropy with characteristic sheared hysteresis loops. The films are fabricated by RF-magnetron sputtering and then patterned with a 50 keV Ga+ focused ion beam (FIB) tool. This keeps surface roughness low and feature sizes in the hundred-nanometer-regime are achievable by a single processing step. Simulations with the well established SRIM (Stopping and Range of Ions in Matter) code give an estimation of the beam diameter and help to estimate the FIB patterning potential. In order to show antiferromagnetic ordering large 48×48 dot arrays of (200×200) nm2 single domain dots were fabricated. The samples were demagnetized and scanned by magnetic force microscopy (MFM) in the remanent state. The demagnetized checkerboard patterns show no frustration over hundreds of dots. The fabricated single domain magnets are prospective building blocks for field-coupled magnetic logic devices.