Magnetoresistance Sensors with Cocr Ferromagnetic Films

Abstract

The magnetic properties of CoCr thin films are studied for the enhancement of the sensitivity of Z-axis tunneling magnetoresistance sensors. We demonstrate that the CoCr film achieves a low saturation magne tization of 45emu/cm3 at a Cr concentration of 35 at%, while maintaining thermal stability up to 400°C. Incorporating this soft ferromagnetic layer into the magnetic free layer allows significant reduction of the anisotropy field, consistent with the simulated results. Spin valves employing CoCr films were fabricated and giant magnetoresistance was measured. It is revealed that the Co/CoCr composite free layer exhibits twice the sensitivity of a pure Co free layer. These findings highlight the potential of CoFeB/CoCr-based structures for improving the sensitivity of magnetoresistance sensors

Keywords: CoCr, Z-axis xMR sensor, spin valve