GMR of Co/Cu multilayers with reduced hysteresis and low-field response

We present results of a study on optimization of the magnetoresistance (GMR) response in Co/Cu multilayers (MLs) for Cu layer thickness near the second oscillatory peak. Co/Cu MLs with alternating thick (t⁽¹⁾_Co) and thin (t⁽²⁾_Co ) Co layers have been prepared in the form of [Cot⁽¹⁾ _Co Å/Cu20 Å/Cot⁽²⁾_Co Å/Cu20 Å]₁₅. We have found that the magnetoresistive hysteresis of these MLs is reduced with decreasing t ⁽²⁾_Co and has disappeared when t⁽²⁾_Co<4.5 Å. We have obtained an optimal GMR response with a field sensitivity of 0.13%/0e over a field region of ~60 Oe centered at ~50 Oe. This architecture may enable the use of Cu/Co MLs in low-field magnetic sensor applications