TY - JOUR
T1 - Superparamagnetic ground state of CoFeB/MgO magnetic tunnel junction with dual-barrier
AU - Tran, Thanh Nga
AU - Lam, Tu Ngoc
AU - Yang, Chao Yao
AU - Lin, Wen Chin
AU - Chen, Po Wen
AU - Tseng, Yuan Chieh
N1 - Funding Information:
This work was financially supported by the “Center for Semiconductor Technology Research” from The Featured Areas Research Center Program within the framework of the Higher Education Sprout Project by the Ministry of Education (MOE) in Taiwan. Also supported in part by the Ministry of Science and Technology, Taiwan , under Grant MOST-107-3017-F-009-002/104-2112-M-009-012-MY3 .
Publisher Copyright:
© 2018 Elsevier B.V.
PY - 2018/11/1
Y1 - 2018/11/1
N2 - CoFeB/MgO-based magnetic tunnel junctions (MTJs) have considerable potential in magnetic random access memory (MRAM), thanks to their tunable perpendicular magnetic anisotropy (PMA). We found significant reduction of dead-layer by inserting additional MgO into the MTJ structure. Interface, electronic and transport characterizations were utilized to approach the modified magnetic properties driven by the dual-MgO structure in this work. The dual-MgO structure appeared to hinder boron (B) diffusion into the metallic layer and prevent capping-layer (Ta) penetration across the interface. This suppressed the dead-layer effect and promoted overall magnetization despite PMA degradation. A robust BO x phase that formed within the dual-MgO structure presented a superparamagnetic ground state. In the single-MgO structure, any reduction in the thickness of the CoFeB promoted PMA, albeit at the cost of spin-polarization. The dual-MgO structure could restore spin-polarization by preferentially populating spin electrons into Fe/Co minority states. X-ray magnetic spectroscopy and anomalous Hall effect suggest that, the dual-MgO differs from the single-MgO with a favorable longitudinal polarized spin-channel. This makes the dual-MgO structure applicable to applications requiring in-plane rather than out-of-plane sensing.
AB - CoFeB/MgO-based magnetic tunnel junctions (MTJs) have considerable potential in magnetic random access memory (MRAM), thanks to their tunable perpendicular magnetic anisotropy (PMA). We found significant reduction of dead-layer by inserting additional MgO into the MTJ structure. Interface, electronic and transport characterizations were utilized to approach the modified magnetic properties driven by the dual-MgO structure in this work. The dual-MgO structure appeared to hinder boron (B) diffusion into the metallic layer and prevent capping-layer (Ta) penetration across the interface. This suppressed the dead-layer effect and promoted overall magnetization despite PMA degradation. A robust BO x phase that formed within the dual-MgO structure presented a superparamagnetic ground state. In the single-MgO structure, any reduction in the thickness of the CoFeB promoted PMA, albeit at the cost of spin-polarization. The dual-MgO structure could restore spin-polarization by preferentially populating spin electrons into Fe/Co minority states. X-ray magnetic spectroscopy and anomalous Hall effect suggest that, the dual-MgO differs from the single-MgO with a favorable longitudinal polarized spin-channel. This makes the dual-MgO structure applicable to applications requiring in-plane rather than out-of-plane sensing.
KW - Magnetic random access memory
KW - Magnetic tunnel junction
KW - Perpendicular magnetic anisotropy
KW - Spin-valve
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U2 - 10.1016/j.apsusc.2018.06.292
DO - 10.1016/j.apsusc.2018.06.292
M3 - Article
AN - SCOPUS:85049840642
SN - 0169-4332
VL - 457
SP - 529
EP - 535
JO - Applied Surface Science
JF - Applied Surface Science
ER -