Nano-imprinting potential of magnetic FeCo-based metallic glass

Abstract

Fabrication of magnetic nanostructures at low cost is strongly desired for applications such as sensors, actuators, magnetic memory, etc. In conventional nano-patterning techniques, the magnetic field of a magnetic material interferes with the patterning process, making nano-patterning challenging. Here, we report on the low cost patterning potential of FeCo-based magnetic metallic glass using a nano-imprinting technique. We show that out of a large number of magnetic metallic glasses, Fe40Co35P10C10B5 glassy alloy exhibits high saturation magnetic flux density (Bs ∼ 1.24 T), a large super-cooled liquid temperature range (ΔTx ∼ 49 °C), and a relatively low glass transition temperature (Tg ∼ 430 °C) with good thermal stability. The quasi-static viscosity (∼108 Pa.s at a heating rate of ∼40 °C min−1) in ΔTx, which is one of the most important parameters for nano-imprinting, is lowest among the reported magnetic metallic glasses. The deformability of this magnetic alloy is similar to the well-known non-magnetic metallic glasses, which can be patterned to a few tens of nanometers. Crystallization of Fe40Co35P10C10B5 glassy alloy leads to the precipitation of a high Bs FeCo phase that may exhibit high magnetocrystalline anisotropy. Based on detailed investigations of structural, thermal, and magnetic behavior, along with imprinting experiments, we show that the Fe40Co35P10C10B5 glassy alloy is the most desirable material for making various nano-patterns with tailorable magnetic properties.