Evolution of magnetic pillars using 200 MeV Ag15+ ion irradiation

Abstract

We have studied the evolution of micro and nano magnetic pillars, created by 200MeV Ag15+ ion irradiation on the surface of Mg0.95Mn0.05Fe2O4 thin films, using X-ray diffraction, atomic force and dc magnetization. Thin films of Mg0.95Mn0.05Fe2O4 were deposited using pulsed laser deposition technique on platinum coated silicon (Pt–Si) substrate. The X-ray diffraction study clearly indicates that the evaluated magnetic pillars have single phase spinel cubic structure. From dc magnetization hysteresis loop, it is observed that the film deposited on Pt–Si exhibits a ferrimagnetic ordering at room temperature and the saturation magnetization increases with fluence value up to 5×1011ions/cm2 which may be due to grain growth. However, with further increase in fluence value, the magnetization decreases, but this value is still larger than that of as-deposited film. The average size of magnetic pillars calculated from atomic force microscopy is found to be ∼63 and ∼121nm at a fluence of 1×1011ions/cm2 and then increases up to ∼136nm at a fluence of 5×1011ions/cm2 and finally, attains a value of ∼107nm at a fluence of 1×1012ions/cm2. The formations of these magnetic nano-pillars are explained on the basis of metallic catalyst assisted growth after SHI irradiation.