Role of dimension size of patterned permalloy films in high frequency applications

Ferromagnetic materials have been extensively used into on-chip passive devices to improve device performance at radio frequencies (RF). A lot of work is in progress to boost up the frequency response of permalloy material in order to incorporate it with RF Inductors. One of them is control of domain dynamics. Therefore to control the domain dynamics it is important to know the factors effecting the high frequency performance. In this work, Double and Single domain permalloy bars with varying dimension sizes have been incorporated with transmission lines. The simulation and measured results show that dimension size of these patterned permalloy films play a crucial role in boosting up the frequency response. It is also observed that a particular size of permalloy bars can be used for a specific range of frequencies. As the dimension of the bar decreases maintaining same domain pattern, the frequency to which it responds can be increased. Finally, effect of surface topography on domain structures and corresponding dynamic processes is also discussed.