Writing 3D Nanomagnets Using Focused Electron Beams

Abstract

Focused electron beam induced deposition (FEBID) is a direct-write nanofabrication technique able to pattern three-dimensional magnetic nanostructures at resolutions comparable to the characteristic magnetic length scales. FEBID is thus a powerful tool for 3D nanomagnetism which enables unique fundamental studies involving complex 3D geometries, as well as nano-prototyping and specialized applications compatible with low throughputs. In this focused review, we discuss recent developments of this technique for applications in 3D nanomagnetism, namely the substantial progress on FEBID computational methods, and new routes followed to tune the magnetic properties of ferromagnetic FEBID materials. We also review a selection of recent works involving FEBID 3D nanostructures in areas such as scanning probe microscopy sensing, magnetic frustration phenomena, curvilinear magnetism, magnonics and fluxonics, offering a wide perspective of the important role FEBID is likely to have in the coming years in the study of new phenomena involving 3D magnetic nanostructures.

Inverse-design magnonic devices

“…It is noted that here we just demonstrate the concept and, for simplicity, use a "binary approach" where each region can have two states: 1 (YIG) or 0 (vacuum). But since the complexity of the functionality of an inverse-design device is fundamentally limited by the number of the degrees of freedom 24,25 , namely by the design space, the following approaches can be used: (1) The switch from the 2D to 3D matrices 38,39 or the incremental engineering of (2) the thickness of the elements 35,40 , (3) the saturation magnetization [40][41][42] , or (4) the exchange stiffness of the magnetic material 42 . An external field of 200 mT is applied out-of-plane along the z-axis, and Forward Volume Spin Waves (FVSWs) are investigated (please note that this is not a classical FV magnetostatic wave (FVMSW) in a plane film since here also exchange energy is taken into account).…”

Focused-Electron-Beam Engineering of 3D Magnetic Nanowires

“…Remarkable applications have been developed in magnetic sensing by functionalization of magnetic probes for magnetic force microscopy [ 22 ] and ferromagnetic resonance force microscopy [ 23 ] in materials science and biology [ 24 ], as magnetically driven mechanical nano-actuators [ 25 ], 3D domain wall conduit [ 26 ], ferromagnetic designs based on 3D FEBID scaffolds [ 18 ], arrays of 3D nanopillars for magnetic logic [ 27 ], 3D artificial ferromagnetic lattices [ 28 , 29 ], and magnetically chiral 3D architectures [ 30 ]. Further examples of applications of 3D FEBID ferromagnets have been reviewed recently by Fernández-Pacheco et al [ 31 ].…”

Fabrication of a 3D Nanomagnetic Circuit with Multi-Layered Materials for Applications in Spintronics

“…Although well suited to the fabrication of extended nanoscale systems, this fabrication route is limited in the choice of geometries and the control over the thickness of the ferromagnetic films grown via chemical synthesis methods, hence hindering the inclusion of functional interfaces [ 6 ]. The second route employs a 3D nano-printing technique [ 17 ], known as focused electron beam induced deposition (FEBID), which allows prototyping of individual complex 3D structures [ 18 ], with tens of nanometre resolution in polycrystalline or amorphous cobalt [ 19 ], iron or cobalt-iron alloys [ 20 , 21 ]. Artificial double-helices which provide controlled magnetic chirality have been realised using this method [ 22 ].…”

“…Artificial double-helices which provide controlled magnetic chirality have been realised using this method [ 22 ]. This route provides significantly more flexibility in the choice of geometry; however, it is limited by the range of materials and cannot be used to create high quality materials and interfaces directly [ 17 ]. The third route involves the use of physical vapour deposition (PVD) on top of previously patterned non-magnetic 3D scaffolds.…”