Magnetization dynamics of micron size thin Permalloy films

The magnetic properties of thin films of NiFe Permalloy of micron dimensions have been investigated both in the presence and absence of a titanium underlayer on silicon oxidized substrates. For those samples possessing a low aspect ratio, the domain walls remain fixed almost throughout the entire range of our external field capacity of 40 Oe—this stability increasing with increasing film thickness. Magnetic moment reversal appears to occur by magnetic moment rotation within the domains rather than by domain wall motion. As the sample length increases in size, we see edge domains at either end but a lack of domain structure through the sample length. The presence of the titanium underlayer increases the stability and produces a marked asymmetry in our domain wall structure as we cycled through the B-H hysteresis loop. All samples displayed a marked increase in the coercive force compared to Permalloy thin films of large size planar dimensions.