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Abstract:
Ta (5)/CoFeB (1)/MgO (2)/Ta (2) (in nm) multilayers were deposited on silicon substrates by magnetron sputtering, and the MgO layer was prepared by two methods at the same argon gas flow rate: the radio frequency (RF) sputtering method of MgO target and the reactive sputtering method of direct current (DC) sputtering Mg target with introducing oxygen at the same time. The sample prepared by the former method was denoted as Sample A, and the latter was denoted as Sample B. The results indicate that as-deposited Sample A shows in plane magnetic anisotropy (IMA) with K-eff =-0.79 x 10(6)erg/cm(3). However, the as-deposited Sample B shows perpendicular magnetic anisotropy (PMA) with K-eff = 1.69 x 10(6)erg/cm(3), and the K-eff value increases to 3.17 x 10(6)erg/cm(3 )after annealing at 250 & DEG;C. X-ray photoelectron spectroscopy (XPS) results illustrate that the films show PMA when the composition ratio (epsilon) of Fe oxide to Fe in CoFeB/oxide interface of Sample A and B annealed below 300 & DEG;C, is approximately in the range of 0.65-0.75. When epsilon is beyond the above range, the film shows IMA. Moderate oxidation state at the interface results in the formation of PMA and it was improved by forming effective orbital hybridization of Fe 3d and O 2p. High resolution transmission electron microscopy (HRTEM) analysis reveals that no crystallization appears in CoFeB and MgO layer of the film before and after annealing, and crystallization has no effect on the interface chemical states in this system.
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Source :
APPLIED SURFACE SCIENCE
ISSN: 0169-4332
Year: 2022
Volume: 585
6 . 7
JCR@2022
6 . 7 0 0
JCR@2022
ESI Discipline: MATERIALS SCIENCE;
ESI HC Threshold:66
JCR Journal Grade:1
CAS Journal Grade:2
Cited Count:
SCOPUS Cited Count: 15
ESI Highly Cited Papers on the List: 0 Unfold All
WanFang Cited Count:
Chinese Cited Count:
30 Days PV: 0
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