Nano-imprinting potential of magnetic FeCo-based metallic glass

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 (B _s  ∼ 1.24 T), a large super-cooled liquid temperature range (ΔT _x  ∼ 49 °C), and a relatively low glass transition temperature (T _g  ∼ 430 °C) with good thermal stability. The quasi-static viscosity (∼10⁸ Pa.s at a heating rate of ∼40 °C min^-1) in ΔT _x , 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 B _s 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.