Artificial Spin Ice (ASI)

Physics and Astronomy – Graduate Student

Artificial spin ice (ASI) structures are frustrated magnetic structures which have degenerate states. In other words, there exist different configurations that has the same energy. Each element acts as a tiny magnet (nano magnet) that its magnetization direction can lie in plane and in longitudinal direction (in either ways). We have been succeeded fabricating this structure both using etching and the lift-off process, both of which are included in the images. In these images, each nano magnet is made of Permalloy (NiFe) that sits on the gold wave guide (CPW) or silicon dioxide substrate (SiO2). If the sample is named with “LiftOff”, then the structure is Permalloy nano magnet sitting on either gold CPW or SiO2. However, if the structure is named with “Etch”, which relates to the etching process, then all the Permalloy nano magnets are coated with HSQ photo resist. Due to their very small dimensions, the fabrication process is challenging. To address that, as it can be seen from the images, they are 260 nm long, 80 nm wide and 15 nm thick. Finally, the smallest gap between each two nanomagnets (which is the most challenging part of the fabrication process) is in the range of 20-30 nm. ASI has many applications from writing and deleting data on magnetic memories to neuromorphic computing (which aim to reduce energy consumption due to replacing wire with ASI).