We present a transfer-function approach to calculate the force on a magnetic force microscope tip and the stray field due to a perpendicularly magnetized medium having an arbitrary magnetization pattern. Under certain conditions, it is possible to calculate the magnetization pattern from the measured force data. We apply this transfer function theory to quantitatively simulate magnetic force microscopy data acquired on a CoNi/Pt multilayer and on an epitaxially grown Cu/Ni/Cu/Si(001) magnetic thin film. The method described here serves as an excellent basis for (i) the definition of the condition for achieving maximum resolution in a specific experiment, (ii) the differences of force and force z-derivative imaging, (iii) the artificial distinction between domain and domain wall contrast, and finally (iv) the influence of various tip shapes on image content.

/pdf/quantitative-magnetic-force-microscopy-on-perpendicularly-2uizkc8kck.pdf

Quantitative magnetic force microscopy on perpendicularly magnetized samples

Magnetic force microscopy of thin film media for high density magnetic recording

The review will describe the various scanning probe microscopy tips and cantilevers used today for scanning force microscopy and magnetic force microscopy. Work undertaken to quantify the properties of cantilevers and tips, e.g. shape and radius, is reviewed together with an overview of the various tip–sample interactions that affect dimensional measurements.

https://iopscience.iop.org/article/10.1088/0022-3727/41/10/103001/pdf

Aspects of scanning force microscope probes and their effects on dimensional measurement

This article describes the design of a versatile ultrahigh vaccum (UHV) low temperature scanning force microscope system The system allows scanning probe microscopy measurements at temperatures between 6 and 400 K and in magnetic fields up to 7 T Cantilevers and samples can be prepared in UHV and transferred to the microscope We describe some technical details of our system and present first measurements performed at different temperatures and in various scanning force microscopy operation modes We demonstrate distortion free and calibrated images at temperatures ranging from 8 to 300 K, atomic resolution on NaCl at 76 K and various magnetic force microscopy images of vortices in high transition temperature superconductors It is demonstrated that our instrumentation reaches the thermodynamically determined sensitivity limit Using standard cantilevers force gradients in the 10−6N/m range, corresponding forces of about 10−15N can be measured

A low temperature ultrahigh vaccum scanning force microscope

Domain structures and switching mechanisms in patterned magnetic elements

We used a new concept of tip preparation for magnetic force microscopy (MFM) proposed recently based on coating electron beam deposited carbon needles with appropriate magnetic thin film materials. In combining the advantages of electron beam fabricated needles with those of already widely used thin film tips, high resolution MFM tips can be prepared routinely and reproducibly on all type of cantilevers. Due to the fabrication procedure, which is described in detail, the effective magnetic tip volume is formed by a homogeneous, magnetically isolated, high aspect ratio thin film element favoring a single domain tip behavior. To reinforce the inherent shape anisotropy an additional uniaxial anisotropy is induced along the tip axis by applying an external field during the deposition of the ferromagnetic alloy. Because of the parallel side walls and the rounded tip end, most of the stray field will emanate from the apex region, resulting in a high field density and only little influence on the magnetization within the sample of interest. By using a material with high saturation magnetization, the thickness of the magnetic layer can be drastically reduced, leading to an increased resolution. To demonstrate the potential of the new concept various MFM observations on different types of materials for magnetic storage technology have been performed without changing the presented basic preparation parameters.

/pdf/magnetic-force-microscopy-using-electron-beam-fabricated-2efge8j8mn.pdf

Magnetic force microscopy using electron-beam fabricated tips

The stray field, magnetic microstructure, and switching behavior of high‐resolution electron beam fabricated thin film tips for magnetic force microscopy (MFM) are investigated with different imaging modes in a transmission electron microscope (TEM). 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.

/pdf/electron-beam-fabrication-and-characterization-of-high-4sqiciwur1.pdf

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

In order to understand the magnetic behaviour of thin film magnetic recording media high resolution magnetic observation techniques are very essential to see magnetic details smaller than 100 ran size. Magnetic Force Microscopy (MFM) is used for analysing thin magnetic films and multilayers as well as for investigation of written bits in high density recording media. Continuous attention is given to increase the performance of the used magnetic tips.

/pdf/magnetic-force-microscopy-on-thin-film-magnetic-recording-3j9a45d0c3.pdf

S. Porthun

Papers

Magnetic force microscopy using electron-beam fabricated tips

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

Magnetic Force Microscopy on Thin Film Magnetic Recording Media

Magnetic force microscopy on thin film magnetic recording media