[20a-B101-1~10] 10.3 Spin devices, magnetic memories and storages

▲ [20a-B101-7] Giant magnetoresistance and interlayer exchange coupling in [FeCoNi/Cu] multilayers with NiFeCr seed layer

〇(P)Prabhanjan Dilip Kulkarni¹, Tomoya Nakatani¹, Zehao Li¹, Taisuke Sasaki¹, Yuya Sakuraba¹ (1.NIMS)

Keywords:Giant magnetoresistance, Interlayer exchange coupling, Microstructure

We present a systematic study on the giant magnetoresistance (GMR) and interlayer exchange couplings (IEC) in polycrystalline [Fe₁₆Co₆₆Ni₁₈/Cu]₅/Fe₁₆Co₆₆Ni₁₈ multilayer films deposited on NiFeCr seed layers with various compositions. The maximum ΔR/R of 35±2.5% and strong antiparallel IEC were observed for the seed layers with a particular Ni:Fe ratio of (Ni_0.55Cr_0.45)_100-yFe_y with 0≤y≤47. Structural studies confirm that this high ΔR/R is related to a strong fcc [111] texture and coarse grains of the GMR films. We also observed that the film deposited on Ni₃₂Fe₃₃Cr₃₅ seed layer showed stronger [111] texture, but lower ΔR/R (17%) than those deposited on Ni₃₆Fe₅₁Cr₁₃ seed layer (ΔR/R=28%). Microstructural analysis indicated an increased arithmetic average roughness (Ra) of the interfaces between FeCoNi and Cu layers for the films with the Ni₃₂Fe₃₃Cr₃₅ seed layer. We argue that this higher Ra causes a reduction in antiparallel IEC and increase a biquadratic (90°) IEC and thus reduce ΔR/R.