Exploiting femtosecond laser exposure for additive and subtractive fabrication of functional materials: A Route to designer 3D Magnetic Nanostructures

TL;DR

This paper demonstrates a novel 3D nanofabrication method combining femtosecond laser exposure and two-photon lithography to create complex functional magnetic nanostructures with potential for advanced electromagnetic applications.

Contribution

It introduces a new additive and subtractive fabrication technique for 3D magnetic nanostructures using femtosecond laser exposure and two-photon lithography, enabling complex geometries.

Findings

Fabricated 3D magnetic nanowires with controlled domain wall behavior

Created large-scale 3D artificial spin-ice structures with tunable switching

Depth-dependent magnetic switching characterized via magneto-optical Kerr effect

Abstract

Three-dimensional nanostructured functional materials are important systems, allowing new means to intricately control electromagnetic properties. A key problem is realising a 3D printing methodology upon the nanoscale that can yield a range of functional materials. In this letter, it is shown that two-photon lithography when combined with femtosecond machining of sacrificial layers, can be used to realise such a vision and produce 3D functional nanomaterials of complex geometry. This is demonstrated by fabricating 3D magnetic nanowires that exhibit controlled domain wall injection and propagation. Secondly, we fabricate large scale 3D artificial spin-ice structures whose complex switching can be probed using optical magnetometry. We show that by careful analysis of the magneto-optical Kerr effect signal and by comparison with micro-magnetic simulations, depth dependent switching information can be obtained from the 3DASI lattice. The work paves the way to new materials, which exploit additional physics provided by non-trivial 3D geometries.