Electron beam fabrication and characterization of high-resolution magnetic force microscopy tips

Abstract

The stray field, magnetic microstructure, and switching behavior of high-resolution electron beam fabricated thin film tips for magnetic force microscopy ͑MFM͒ are investigated with different imaging modes in a transmission electron microscope ͑TEM͒. As the tiny smooth carbon needles covered with a thermally evaporated magnetic thin film are transparent to the electron energies used in these TEMs it is possible to observe both the external stray field emanating from the tips as well as their internal domain structure. The experiments confirm the basic features of electron beam fabricated thin film tips concluded from various MFM observations using these tips. Only a weak but highly concentrated stray field is observed emanating from the immediate apex region of the tip, consistent with their capability for high resolution. It also supports the negligible perturbation of the magnetization sample due to the tip stray field observed in MFM experiments. Investigation of the magnetization distributions within the tips, as well as preliminary magnetizing experiments, confirm a preferred single domain state of the high aspect ratio tips. To exclude artefacts of the observation techniques both nonmagnetic tips and those supporting different magnetization states are used for comparison.

Imaging and Characterization of Magnetic Micro- and Nanostructures Using Force Microscopy

“…They range from etching/milling techniques to sharpen the magnetization volume [106,107,110], mounting of ferromagnetically filled carbon nanotubes onto cantilevers [108,[111][112][113], to attaching ferromagnetic nanospheres onto the cantilever [109]. These examples show impressively that a spatial confinement of the magnetic probe's volume may drastically increase the lateral resolution of MFM measurements [86].…”

Magnetic Force Microscopy — Towards Higher Resolution

“…On the side of these carbon tips, a thin magnetic layer is deposited. Some call these tips Electron Beam Deposited (EBD) tips [5], but to avoid confusion with Electron Beam Evaporation, which is a layer deposition technique, others call these tips Electron Beam Induced Deposited (EBID) tips [26,27]. Especially the tips made by Skidmore et al are impressive, with a tip radius of less than 7 nm.…”

Optimization of lateral resolution in magnetic force microscopy

“…The FTF depends on the shape and the magnetic state of the tip. For a bar-type tip (like the EBID tip [4]) with magnetization M t , width b, depth S and length ∆l it is given by:…”