A magnetoresistance sensor is fabricated using a sensor structure including a free layer deposited upon a lower layered structure and depositing an oxide structure overlying the free layer. The depositing of the oxide structure includes the steps of depositing a buffer layer overlying the free layer, wherein the buffer layer is a buffer-layer metal when deposited, depositing an overlayer overlying and contacting the buffer layer, the overlayer being an overlayer metallic oxide of an overlayer metal, and oxidizing the buffer layer to form a buffer layer metallic oxide.