Magnetic Force Microscope Tip with High Resolution and High Switching Field Prepared by Coating Si Tip with L11 Ordered CoPt-Alloy Film

Abstract

Magnetic force microscope (MFM) tips are prepared by coating Si tips of 4 nm radius with CoPt-alloy films at 300 °C varying the thickness in a range between 10 and 200 nm. L11 ordered phase formation is recognized for the CoPt film. The influences of coating thickness on the spatial resolution and the switching field of MFM tip are investigated. With increasing the thickness from 10 to 30 nm, the resolution improves from 10.2 to 7.3 nm due to an increase of signal detection sensitivity related with the remanent magnetization (Mrt) of coated film. As the thickness further increases, the resolution decreases due to an increase of tip radius. The resolution is influenced by both the detection sensitivity and the tip radius. The switching field monotonically increases from 1.7 to 5.8 kOe with increasing the thickness from 10 to 200 nm. High switching fields are obtained, which are interpreted to be reflecting the magnetocrystalline anisotropy of L11 ordered phase included in CoPt film. An MFM tip coated with CoPt film including L11 ordered phase is useful for the observation of magnetic domain structures of future HDD media and permanent magnets.

A Review of the Current State of Magnetic Force Microscopy to Unravel the Magnetic Properties of Nanomaterials Applied in Biological Systems and Future Directions for Quantum Technologies

“…As already mentioned in Section 5 , the most intuitive approach is to reduce the thickness of the coating and/or to use ultra-sharp AFM tips as a scaffold [ 300 ] ( Figure 9 a). This can reduce the radius down to 15 nm (e.g., SSS-QMFMR from NANOSENSORS TM [ 301 ]), but at the expense of the magnetic properties [ 302 ] due to the reduced material volume, while the increased risk of delamination still remains. The second option is to sputter only one side of the tip, which effectively reduces the tip radius [ 303 ].…”

Fabrication of Tips for Magnetic Force Microscopy Employing Magnetic Multilayer Structures

“…Tip is a key component in an MFM system which determines the spatial resolution. MFM tips are generally prepared by coating non-magnetic sharp tips with magnetic films [1][2][3][4][5][6][7][8][9][10][11]. Future magnetic recording media of hard-disk-drives (HDDs) will employ magnetic materials with high uniaxial magnetocrystalline anisotropy energies (K u ) such as FePt and SmCo 5, where the MFM tip will be exposed to a high magnetic field in the MFM observation.…”

Development of Media Nanostructure for Perpendicular Magnetic Recording

“…Since the spatial resolution of commercially available MFM tip was limited at around 20 nm, the structure and the magnetic material for MFM tip fabrication were systematically investigated to improve the spatial resolution and the magnetic switching field [115][116][117][118][119] . High magnetic switching field is required for an MFM tip in the magnetization structure observation of high coercivity medium, where the tip is exposed to a strong magnetic flux emanating from the sample that may change the tip magnetization.…”

“…Through optimization of tip fabrication condition, MFM tips with spatial resolutions of 6 -7 nm could be developed 123,124) . The switching field was increased to be higher than 2 kOe with maintaining high spatial resolutions of 10 nm or better 117,125) . Figure 12 shows the magnetization structure of 500 - 1100 kFCI (bit length: 51 -23 nm) recorded on a CoCrPtSiOx PMR medium observed by employing a highresolution tip 119) .…”