کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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5435693 | 1509534 | 2018 | 9 صفحه PDF | دانلود رایگان |
We studied the origin of the enhancement of current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) effect by inserting a thin amorphous CoFeBTa (CFBT) underlayer below a Co2(Mn0.6Fe0.4)Ge (CMFG) Heusler alloy ferromagnetic (FM) layer. Large magnetoresistance ratio of â¼25% and resistance change-area product of â¼7.5 mΩ μm2 were obtained at room temperature by inserting a CFBT (1.2 nm) underlayer. X-ray diffraction (XRD) and transmission electron microscope analyses confirmed that the CMFG FM layer deposited on the CFBT underlayer was amorphous in the as-deposited state and crystallized to a B2-ordered polycrystalline film by annealing at 300 °C. The degree of B2 order (SB2) of the CMFG films was estimated by anomalous XRD using x-ray energies around the Co K-absorption edge. SB2 of the CMFG film deposited on the amorphous CFBT (1.2 nm) underlayer was â¼0.76, much larger than that of the CMFG film deposited on a crystalline CoFe underlayer (SB2 â¼0.47). First-principles calculations indicated that the spin polarization of the sp-conduction electrons in CMFG increases with increasing SB2, which accounts for the enhanced CPP-GMR effect in the pseudo spin-valve by inserting an amorphous CFBT underlayer.
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Journal: Acta Materialia - Volume 142, 1 January 2018, Pages 49-57