The advantages of the magnetic structure in ferromagnetic-film-coated carbon nanotube probes

Abstract

The magnetic structures of ferromagnetic-film-coated carbon nanotube (CNT) probes and conventional pyramidal probes for a magnetic force microscope (MFM) were simulated using three-dimensional micromagnetic simulation. The CNT-MFM probes with a total probe diameter less than 60 nm are almost uniformly magnetized along the longitudinal direction of the CNT, which is the ideal magnetic structure for MFM observations. On the other hand, the pyramidal probes had a vortex structure around the point tip, which suggests that they require a greater thickness of the ferromagnetic film because only part of the magnetic moment participates in the detection of the z-component of the stray field from samples. The advantages of the CNT-MFM probe are uniform magnetization along the longitudinal direction and magnetic imaging ability using a smaller coating thickness.

Spatial resolution and switching field of magnetic force microscope tip coated with FePd-alloy thin film

“…The The enhancement is possibly due to an influence of shape magnetic anisotropy. The magnetization state of MFM tip has been studied by using micromagnetic simulations [12][13][14]. It seems necessary to investigate the magnetization reverse process of FePdcoated tip by such theoretical calculations.…”

Magnetic Force Probe Characterizations of Nanoscaled Ferromagnetic Domains: Finite-Element Magnetostatic Simulations

“…Micromagnetism model based on micromagnetic theory is a hot topic of MFM technology. Compared with pyramid probe tip, the micromagnetism model has been successfully applied to simulate the MFM with a carbon nanotube probe coated by Co ferromagnetic film (CNT-MFM), which demonstrates that CNT-MFM can achieve a sufficiently high resolution to measure perpendicular magnetic recording disks [14]. Furthermore, Mansuripur modeled the magnetic coated tip as a tetrahedron by an ensemble of cube elements, and Oti proposed a model of 2D triangle structure, while Tomlinson performed micromagnetic simulations with a 3D pyramid model, all of which were successful micromagnetism model paradigms by solving Landau-Lifshitz-Gilbert equations of micromagnetic theory [15][16][17].…”

Optimal ferromagnetically-coated carbon nanotube tips for ultra-high resolution magnetic force microscopy

“…Magnetic force microscopy (MFM) is commonly used due to its high resolution and convenience, with significant enhancement in imaging efficiency due to the recent introduction of ferromagnetic-thin-film-coated carbon nanotube (MFM-CNT) tips [11][12][13]. The combination of the small diameter and high aspect ratio of carbon nanotubes results in the formation of a well defined magnetic volume with high anisotropy, allowing both soft and hard magnetic materials to be accessed [11][12][13][14][15][16]. The small volume of magnetic metal coating at the tip leads to improved resolution, with magnetic domains in storage media imaged at ultra-high densities from 700 to 1400 kFCI (200-350 Gbin −2 ) [13,16].…”

“…The combination of the small diameter and high aspect ratio of carbon nanotubes results in the formation of a well defined magnetic volume with high anisotropy, allowing both soft and hard magnetic materials to be accessed [11][12][13][14][15][16]. The small volume of magnetic metal coating at the tip leads to improved resolution, with magnetic domains in storage media imaged at ultra-high densities from 700 to 1400 kFCI (200-350 Gbin −2 ) [13,16]. At the same time, the magnetic field of such tips is sufficiently weak not to perturb the magnetization of permalloy thin film microstructures, allowing the nanoscale observation of vortex cores and domain walls in these materials [14].…”