High magnetoresistance permalloy films deposited on a thin NiFeCr or NiCr underlayer

Abstract

Significantly enhanced anisotropic magnetoresistance (MR) in permalloy (Ni0.81Fe0.19) films deposited on a thin (Ni0.81Fe0.19)1−xCrx or Ni1−xCrx underlayer is reported. The maximum ΔR/R enhancement was observed using the underlayer with x≈0.44 at an optimum thickness of ≈30–45 Å, depending on the deposition technique. An enhancement of 75%–150% was observed for 45–430 Å thick permalloy films, compared to the films deposited without this underlayer. The ΔR/R enhancement is attributed to the decrease in the resistivity ρ and the increase in Δρ of the permalloy film due to the formation of large (111) textured crystal grains in the permalloy films deposited on this underlayer, as revealed by the x-ray diffraction results obtained using synchrotron radiation.

Effect of nano-oxide layers on the magnetoresistance of ultrathin permalloy films

“…When the NiFe layer is thicker than 20 nm, the larger MR ratio of set (I) may be due to the larger grain size and stronger NiFe (111) texture. This is consistent with the results observed by Lee et al [21]. However, for the samples which are less than 15 nm, ΔR/R of set (II) is always greater than that of set (I) despite of the smaller grain size and weaker NiFe (111) texture.…”

High magnetoresistance in sputtered Permalloy thin films through growth on seed layers of (Ni/sub 0.81/Fe/sub 0.19/)/sub 1-x/Cr/sub x/

“…Bilayer Permalloy/NiFeCr films are thermally stable up to about 450 C, since no degradation in was observed until annealing above 450-500 C (depending on Permalloy thickness). Indeed, for these films generally increased by ≈10% after annealing at up to 400 C. As an example, for a 246 Å Permalloy film deposited on a NiFeCr seed layer increases from 3.65% to 3.95% after annealing at 300 C for 2 h, and to 4.10% after further annealing at 450 C for 2 h. The remarkable thermal stability of these films is in contrast to the poor thermal stability of Ta seeded films, where interdiffusion between the Ta and Permalloy is significant at 300 C [13], [18]. High thermal stability and were also observed for the trilayer sensors consisting of 102 Å NiFeNb/30 Å Ni 0.49 Fe 0.12 Cr 0.39 /120 Å Ni 0.81 Fe 0.19 /30 Å Ni 0.49 Fe 0.12 Cr 0.39 deposited by ion-beam sputtering, as can be seen from the and R data obtained before and after post-annealing at 250 and 350 C for ≈7 h, shown in Table I.…”

Probing exotic magnetic phases and electrical transport in Cr-rich γ-NiFeCr alloys

“…19 ) films deposited on thin (Ni 0.81 Fe 0.19 ) 1 À x Cr x underlayers for x¼0.44 Cr at an optimum thickness of 30-45 Å for 45-430 Å thick permalloy films, compared to the films deposited without this underlayer. This enhancement in AMR is attributed to the formation of large (111) textured crystal grains in the permalloy films as revealed by the synchrotron X-ray diffraction results [1]. The complex magnetic properties can be understood by antiferromagnetic exchange interaction between Cr atoms from which a competition arises between ferromagnetic and antiferromagnetic exchange interactions.…”