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

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