Nano-imprinting potential of magnetic FeCo-based metallic glass.

Fabrication of magnetic nanostructures at low cost are strongly desired for applications such as sensors, actuators, magnetic memories etc.. In a conventional nano-patterning techniques, magnetic field of a magnetic material interferes with the patterning process, and makes nano-patterning challenging. Here, we report on a low cost patterning potential of FeCo-based magnetic metallic glass using nano-imprinting technique. We show that out of a large number of magnetic metallic glasses, Fe<sub>40</sub>Co<sub>35</sub>P<sub>10</sub>C<sub>10</sub>B<sub>5</sub> glassy alloy exhibits high saturation magnetic flux density (B<sub>s</sub> ~1.24T), large super-cooled liquid temperature range (ΔT<sub>x</sub>~ 49 <sup>o</sup>C), and relatively low glass transition temperature (T<sub>g</sub>~430<sup> o</sup>C) with good thermal stability. The quasi-static viscosity (~ 10<sup>8</sup> Pa.s at a heating rate of ~ 40 <sup>o</sup>C/minute) in ΔT<sub>x</sub>, 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 few tens of nanometers. Crystallization of Fe<sub>40</sub>Co<sub>35</sub>P<sub>10</sub>C<sub>10</sub>B<sub>5</sub> glassy alloy leads to precipitation of high B<sub>s</sub> Fe-Co phase that may exhibit high magneto-crystalline anisotropy. Based on detailed investigations of structural, thermal and magnetic behavior, along with imprinting experiments, we show that the Fe<sub>40</sub>Co<sub>35</sub>P<sub>10</sub>C<sub>10</sub>B<sub>5</sub> glassy alloy is the desired material for making various nano-patterns with tailorable magnetic properties.