The study of perpendicular magnetic tunnel junctions based on DyFeCo alloys

• Main Authors: Xin-Yu Tsai, 蔡欣妤
• Other Authors: Te-Ho Wu
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/13724635620480607382

碩士 === 國立雲林科技大學 === 材料科技研究所 === 99 === This study focuses on the perpendicular magnetic tunnel junctions (pMTJs) based on dysprosium-iron-cobalt (DyFeCo) and cobalt-iron-boron(Co20Fe60B20) alloys. The full structure of the junctions was SiOx|Ta (5 nm)|Ru(10 nm)|Ta (5 nm)|Co20Fe60B20 (1～1.8 nm)|MgO (2 nm)|Co20Fe60B20 (0 or 1.2 nm)|Dy26(Fe81.7Co18.3)74 (8 nm)|Ta (5 nm)|Ru(10 nm). The DyFeCo layer was served as the fixed layer and the atomic ratio of dysprosium was tuned to induce large coercivity and perpendicular magnetic anisotropy (PMA). Because the MgO-based MTJs need annealing higher than 300 to form bcc (001) structures, it is important to study whether the DyFeCo layer can maintain its PMA after annealing treatment. In addition, the effect of electrode layers was also studied. The magnetic properties were measured by Alternating Gradient Magnetometer (AGM). For the as-deposited samples, insertion of an additional Co20Fe60B20 layer adjacent to DyFeCo layer leads to substantial reduction of corecivities of the fix layers. After annealing treatment, the coercivities and PMA decreased with increasing of annealing temperature. However, we found that the endurance to annealing can be improved substantially with a 5 kOe magnetic field during annealing. Moreover, the choices of the electrode layers did not affect the magnetic properties of the junctions. The experimental results suggested that [Ta|Ru]2|Ta|CoFeB|MgO|CoFeB|DyFeCo|[Ta|Ru]2 was the best structure with suitable coercivities for both free and fix layers after annealing treatment up to 400 .