Optimization of CoFeB Electrodes for Magnetic Tunnel Junctions

A magnetic tunnel junction (MTJ) is the current standard for converting magnetic information into electrical information. It is formed by sandwiching an insulating barrier between two ferromagnetic electrodes. An external magnetic field is then used to switch the electrodes between parallel and antiparallel magnetic alignment. The focus of this research is to optimize the switching between magnetic states through the optimization of electrode thicknesses, especially when non-conventional barrier materials are used. The goal is to decouple the two FM layer switching fields, which allows read-out of two resistance states of the device. The method used is three-fold: First, MTJ stacks are grown using sputter deposition. Next, vibrating sample magnetometry is used to test for switching of magnetic alignment. Finally, atomic force microscopy is used to test for interfacial roughness, which could cause the layers to couple and prohibit antiparallel alignment. I will discuss our work developing a method for minimizing the coupling between the FM electrodes by focusing on understanding the interfacial roughness.