Low temperature MFM imaging of Fe₂₊xV₂₊xAl intermetallics

Abstract

A low temperature magnetic force microscope (MFM) system was set up by adapting a commercial atomic force microscope (AFM) from Park Scientific Instruments (PSI) for low temperature MFM use. Magnetic cantilevers were fabricated for the low temperature MFM system using two methods: by gluing Co particles onto the cantilever tip and by evaporating a Co thin film onto the cantilever tip. Samples of Fe[]V[]Al intermetallics (x = 0, x = 0.1, and x = 0.25) were polished and subsequently studied using the low temperature MFM system at temperatures between 77 K and room temperature. The images obtained give convincing evidence of the development of local magnetic clusters within the material. We found that the magnetic phase transition due the formation of these clusters occurs at about 230K and is independent of composition. We observed further transitions in the x = 0.1 and the x = 0.25 compositions at around 130 K, in which grouping of local clusters appear. Magnetic susceptibility measurements give further evidence of these transitions.