Study of the Underlayer of a PdPtMn Spin-Valve Film

We investigated the PdPtMn bottom spin-valve, which had an high resistivity NiFeCr underlayer. The MR ratio of the NiFeCr-underlayer spin-valve became 1.14 times higher than that of a NiFe-underlayer, because the shunt loss of the underlayer was reduced, and the Hua of the pinned layer also became higher. We found by X-ray diffraction that a PdPtMn spin-valve with a Ta/NiFeCr underlayer had a strong (111) texture. Cross-sectional TEM observation revealed that PdPtMn on a NiFeCr underlayer had a larger grain than PdPtMn on a Ta underlayer. The initial layer of the PdPtMn with the NiFeCr underlayer had a stronger (111) orientation than the PdPtMn with the Ta underlayer. To achieve a large Hua, PdPtMn with a (111) texture and large grain size is required. We simulated the R-H curves of the spin-valve in the head shape. The shift in the quiescent operating point on the R-H curve was smaller for an NiFeCr underlayer than for an NiFe one.