A magnetometry study of Co oxidation in Co/MgO bilayers grown by sputtering

One of the critical challenges during fabrication of magnetic tunnel junctions is to avoid the magnetic bottom electrode oxidation, considered as a spin depolarization source that lowers the tunneling magnetoresistance effect. In this paper, we present a study of the magnetic properties of Co/MgO bilayers as a function of several sputtering growth parameters by using a superconducting quantum interference device magnetometer. We demonstrate the high sensitivity of the magnetic properties to the oxidation of the Co layer and identify the relevant parameters to optimize the MgO growth process.