Giant magnetoresistive sensor with a high resistivity free layer

摘要

A spin valve (SV) magnetoresistive sensor is provided having an AP-pinned layer, a laminated ferromagnetic free layer and a non-magnetic electrically conductive spacer layer sandwiched between the AP-pinned layer and the free layer. The AP-pinned layer comprises first and second ferromagnetic layers separated by an antiparallel coupling (APC) layer. The laminated free layer comprises a third ferromagnetic layer of Co-Fe adjacent to the spacer layer and a fourth ferromagnetic layer of Co-Fe-Hf-O. The Co-Fe-Hf-O material of the fourth ferromagnetic layer has high resistivity resulting in reduced sense current shunting by the free layer. In addition, the metal oxide material of the fourth ferromagnetic layer is known to cause specular scattering of electrons. The reduced sense current shunting and the specular scattering of electrons both contribute to improving the GMR coefficient of the SV sensor.