The Magnetic Reversal Study of Permalloy Microdomains

For studying the influence of the current passed through a metal line for the magnetic cells on semiconductors, we prepared two types of the devices. Case 1 is that only one patterned permalloy cell on top of the insulated metal strip, and two cells are beside the strip. Case 2 is that all three patterned magnetic cells are on top of the strip. The magnetic field needed to reverse the magnetization of a submicrometer-size permalloy single domain cell with aspect ratio of 6 is larger than that of a unpatterned millimeter-size permalloy thin film due to the dimension effect. Magnetic force microscopy images of the patterned cells before and after applying various electrical currents were investigated. We have observed that: 1) the magnetic field produced by the word line will not change the magnetic configuration of the magnetic cells near the wires; 2) the magnetic field produced by the word line is quite uniform; and 3) for small aspect ratio of the submicrometer magnetic cells (<6), the magnetic configuration becomes multidomain, and higher magnetic field needed to reverse its magnetic state. Finally, we have shown a method that integrates an electric wire on semiconductors for generation of surrounding magnetic fields and patterned magnetic cells on micrometer length scales.