Study of fractal dimension and power spectral density analysis of superconductor/ferromagnetic bilayer

Atomic force microscopy investigations through power spectral density analysis and fractal dimension analysis of crack surface due to swift heavy ion (897.6 MeV Xe) irradiation on YBa2Cu3O7−δ and YBa2Cu3O7−δ/La0.67Sr0.33MnO3 PLD thin films have presented. Lattice disorder and suppression of crystallinity of the film has been reported through Ion irradiation. The grain size reduction coupled with development of cracks at higher fluence ∼3 × 1012 ions/cm2 has been observed. The width of the cracks has increased with increase of fluences and is more prominent in bilayer films. The grain size decreased with increasing ion fluence, which led to reduced surface roughness. Swift heavy ion irradiation causes surface diffusion, volume diffusion and strain relaxation in nanoparticles thin films which appear to be responsible for the pragmatic particle size reduction. Power spectral density analyses of AFM data followed by fractal model and K-correlation model have been explained. The crack formation in the above thin films due to irradiation is responsible for the above related phenomena along with the tensile stress which causes surface instability.