Rare-earth material free permanent magnets, such as hard-ferromagnetic alloys and compounds, are incredibly useful in novel magnetic-microelectromechnical systems (MEMS) for biomedical-science, ICT and spintronic based devices — cornerstones of today’s miniaturised tech world. Developing more efficient and cost-effective micromagnets in MEMS-NEMS scale is highly restrained due to the detrimental effects of scaling and demagnetising field as well as lack of hard-magnetic material compatible with CMOS integration.
Cobalt-rich CoPt alloys are a promising group of materials for these applications due to their magnetic properties. In a new paper by Mallick et al., which recently featured as a scientific highlight in Scilight, by the American Institute of Physics, the Micropower Systems & Nanomagnetics team here at Tyndall report a new fabrication process and material characterisations for the Co-rich CoPtP films as a potential candidate for MEMS.
The researchers developed thicker films (thicknesses ranging up to 26 micrometers) and extensively studied the nature of size dependent magnetisation reversal indicating unique interplay of multiple magnetic interactions which provides an opportunity of overall tunability
With the aim of creating smooth, crack-free thicker films, they used an electrochemical bath with additives, and combined with a pulse-reverse technique that employs forward and reverse pulses with optimised duty cycles. They also demonstrated intelligent and novel design strategy by suitable micro-patterning of the Co-rich CoPtP magnet arrays with the motivation of maximizing the electromagnetic coupling necessary for higher efficiencies of the fabricated magnetic-MEMS devices.
Exhaustive simulation results supporting this work provides a roadmap to optimise the shape, interspacing and aspect-ratio of these patterned micro-magnets for enhancing the overall performance suitable for wider-range of MEMS-applications such as MEMS mechanical energy harvesters powering wireless sensor nodes for ‘Internet of Things’.