Magnetic Force Microscopy Of Magnetic Domains In Magnetic Thin Film Of Nano Research

Domain structure and its movement determine the physical properties of ferromagnet. Investigation of domains is the precondition to study macroscopic properties of ferromagnet. There are many methods to investigate domains, such as Bitter Patterns, Magneto-Optical Methods, Transmission Electron Microscopy, Electron Reflection and Scatting Methods, X-ray Neutron and so on. However, these methods suffer from some serious disadvantages involving complex sample preparation, damage to sample, low resolution. The magnetic force microscopy (MFM) is a variant of the Scanning Force Microscopy, which measures the magnetostatic forces or force gradients between a sample and a small ferromagnetic tip. Because of its simple operation, high resolution without the need for special sample preparation, MFM has been widely used in all research fields of ferromagnet. MFM is an effective method to study magnetic domains and research magnetic materials. This paper investigates the nanomagnetic domain by using MFM. The imaging principle of MFM is theoretically analyzed, and the influence of parameters of instrument, stray field from the tip, roughness of sample, vacuum condition, magnetic direction of tip is studied. The interferences between topography and magnetic image are studied in order to improve the qualification of the images. The work provides the foundation of studying domain structure in ferromagnetic thin films. In this work we explored using MFM the domain structure of the as-deposited TbFe films prepared under different sputtering parameters, including film thickness and oblique deposition angles. When the film thickness increasing, the easy direction of magnetization is changed from in-plane to out-plane (maze pattern) . With further increasing the thickness, the maze magnetic domains become wider. The easy direction of magnetization is affected by deposition angles and is found to be paralleled to the substrate with raising deposition angles. The magnetic domains of micro-scale NiFe thin-film magnetic elements are revealed by MFM. Some novel domains are observed.