Effect of surface modification treatment on top-pinned MTJ with perpendicular easy axis

Autor: H. Honjo, H. Naganuma, T. V. A. Nguyen, H. Inoue, M. Yasuhira, S. Ikeda, T. Endoh
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: AIP Advances, Vol 11, Iss 2, Pp 025211-025211-5 (2021)
Druh dokumentu: article
ISSN: 2158-3226
DOI: 10.1063/9.0000047
Popis: We investigated the effects of surface modification treatment (SMT) on the perpendicular magnetic anisotropy (PMA) and the thermal tolerance of top-pinned magnetic tunnel junctions (MTJs) with a Co/Pt synthetic ferrimagnetic coupling reference layer. Applying an SMT to the bottom Pt layer increased the PMA of the overlying Co/Pt multilayer. X-ray diffraction spectrum analysis revealed that the SMT resulted in a higher crystallinity and smaller lattice spacing in the Co/Pt multilayer in the thinner bottom Pt layer, which may have increased the PMA in the Co/Pt multilayer. The tunnel magnetoresistance (TMR) ratio of the MTJ with SMT increased as the annealing temperature was increased up to 400 °C; conversely, the TMR ratio of the MTJ without SMT decreased at an annealing temperature of 400 °C. Evaluation of the m-H loops revealed that, after annealing at 400 °C, the reference layers in the MTJs after SMT possessed better magnetic properties than those in the MTJs without an SMT; this is attributable to the higher PMA of the reference layers with SMT. EDX line analysis revealed that SMT suppressed Pt diffusion to the MgO barrier, resulting in a higher thermal tolerance and larger PMA of the reference layer.
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