Magnetic state instability of disordered electrodeposited nanogranular Fe films

Abstract

The magnetic properties of Fe are exploited in variety of different nanotechnological applications. The electrodeposition conditions have strong influence on resulting properties of Fe films. In this study different methods were used to identify and characterise the morphology and the magnetic properties of Fe films of various thickness electrodeposited at different temperatures. The studied electrodeposited Fe films had elongated structural components orientated mostly perpendicularly to the surface, which caused the magnetisation tilt from the surface of the film. The electrodeposition at 20°C led to more fine and disordered structure compared to the structure obtained at higher electrodeposition temperature, i.e. 65°C. . By applying magnetic field perpendicular to the surface, the minor hysteresis loops of the sample electrodeposited at 20°C changed significantly with repeated measurements. The loop shape depended on initial conditions, probably on the variable magnetic state left after previous magnetisation or on the changes in sample position caused by small angle differences. The analysis of first order reversal curves showed that the magnetisation switching field (pseudo-coercivity) depended on magnetisation at reversal magnetic field, considerably only for 20°C thin film. The magnetic peculiarities of thin film grown at 20°C can be explained by the competing influence of the dipolar interactions and shape anisotropy of vertically elongated grains, and the presence of intergranular soft magnetic material.