Evolution of magnetic pillars using 200 MeV Ag15+ ion irradiation

We have studied the evolution of micro and nano magnetic pillars, created by 200 MeV 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 spinet 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 x 10(11) ions/cm(2) 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 similar to 63 and similar to 121 nm at a fluence of 1 x 10(11) ions/cm(2) and then increases up to similar to 136 nm at a fluence of 5 x 10(11) ions/cm(2) and finally, attains a value of similar to 107 nm at a fluence of 1 x 10(12) ions/cm(2). The formations of these magnetic nanopillars are explained on the basis of metallic catalyst assisted growth after SHI irradiation. (C) 2008 Elsevier B.V. All rights reserved.