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Enhancement of current-perpendicular-to-plane giant magnetoresistive outputs by improving B2-order in polycrystalline Co2(Mn0.6Fe0.4)Ge Heusler alloy films with the insertion of amorphous CoFeBTa underlayer.
- Source :
-
Acta Materialia . Jan2018, Vol. 142, p49-57. 9p. - Publication Year :
- 2018
-
Abstract
- 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 Co 2 (Mn 0.6 Fe 0.4 )Ge (CMFG) Heusler alloy ferromagnetic (FM) layer. Large magnetoresistance ratio of ∼25% and resistance change-area product of ∼7.5 mΩ μm 2 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 ( S B2 ) of the CMFG films was estimated by anomalous XRD using x-ray energies around the Co K- absorption edge. S B2 of the CMFG film deposited on the amorphous CFBT (1.2 nm) underlayer was ∼0.76, much larger than that of the CMFG film deposited on a crystalline CoFe underlayer ( S B2 ∼0.47). First-principles calculations indicated that the spin polarization of the sp -conduction electrons in CMFG increases with increasing S B2 , which accounts for the enhanced CPP-GMR effect in the pseudo spin-valve by inserting an amorphous CFBT underlayer. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 13596454
- Volume :
- 142
- Database :
- Academic Search Index
- Journal :
- Acta Materialia
- Publication Type :
- Academic Journal
- Accession number :
- 125787577
- Full Text :
- https://doi.org/10.1016/j.actamat.2017.09.046