Spin valves with Conetic based synthetic ferrimagnet free layer

Abstract

The detection of low magnetic field requires hysteresis-free magnetoresistive sensor with high sensitivity. Giant magnetoresistance spin valve (SV) sensors with CoFeB based synthetic antiferromagnetic (SAF) pinned layer and Conetic based synthetic ferrimagnet (SF) free layer are developed in this paper. Low free layer coercivity (HC) of 0.27 Oe is achieved through adapting synthetic antiferromagnetic pinned layer in SV with Conetic single free layer. In SV with SAF pinned layer and SF free layer, the MR ratio, HC, switching field (HSW) and offset field (HO) increase with the thickness of the Conetic alloy layer right above the Cu spacer. The HC, HO, and HSW show oscillatory behavior with the Ru spacer thickness in the SF free layer. Through introducing CoFeB/SF free layer, an increased sensitivity of 0.27%/Oe and a small coercivity of 0.3 Oe are attained, which holds promise for low field sensing applications.