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Non-destructive patterning of 10nm magnetic island array by phase transformation with low-energy proton irradiation

Dutta, Tanmay
PATHAK, Sachin
ASBAHİ, Mohamed
Celik, Kubra
Lee, Jong Min
Yang, Ping
Saifullah, M. S. M.
Oral, Ahmet
Bhatia, C. S.
CHA, Jongin
HONG, Jongill
Yang, Hyunsoo
Nano-patterning on the order of sub-10 nm is integral to achieve high-density nano-scale devices for various data storage and data processing applications. However, the additional requirement of planarization and unwanted side-effects of physical or chemical etching have so far limited the patterning of sub-10nm devices. In this work, we have demonstrated the creation of an array of similar to 10nm ferromagnetic islands through selective phase transformation of paramagnetic multilayers by low-energy proton irradiation. Paramagnetic Co3O4/Pd multilayers masked with patterned PMMA (polymethyl methacrylate) were reduced to ferromagnetic Co/Pd by proton irradiation. A clear contrast of the nano-islands was observed using magnetic force microscopy, establishing the formation of ferromagnetic nano-islands with perpendicular magnetic anisotropy. This process provides a way to circumvent the side-effects associated with both conventional nano-scale pattering and high-energy ion irradiation. Therefore, phase transformation by low energy proton irradiation can be used for patterning sub-10nm nano-islands, not only for magnetic data storage but also for patterning various opto-electronic and spintronic devices. Published by AIP Publishing.