Effect of (CoxFe1−x)80B20 Composition on the Magnetic Properties of the Free Layer in Double-Barrier Magnetic Tunnel Junctions

作     者：Shalabh Srivastava Andy Paul Chen Tanmay Dutta Rajagopalan Ramaswamy Jaesung Son Mohammad S. M. Saifullah Kazutaka Yamane Kangho Lee Kie-Leong Teo Yuan Ping Feng Hyunsoo Yang 

作者机构：Department of Electrical and Computer Engineering National University of Singapore Singapore 117576 Department of Physics National University of Singapore 2 Science Drive 3 Singapore 117542 NUS Graduate School of Integrative Sciences and Engineering National University of Singapore 28 Medical Drive Singapore 117456 Singapore GLOBALFOUNDARIES Singapore Pte. Ltd. 60 Woodlands Industrial Park D Street 2 Singapore 738406 Institute of Materials Research and Engineering A*STAR (Agency for Science Technology and Research) 2 Fusionopolis Way #08-03 Innovis Singapore 138634 

出 版 物：《Physical Review Applied》 (Phys. Rev. Appl.)

年 卷 期：2018年第10卷第2期

页      面：024031-024031页

核心收录：

学科分类：07[理学] 0702[理学-物理学] 

基　　金：NRF Industry  (R-263-000-C26-281) 

主　　题：Ferromagnetism Magnetic anisotropy Magnetization switching Spin transfer torque Spintronics Alloys Magnetic tunnel junctions Ferromagnetic resonance 

摘      要：The alloy Co−Fe−B finds extensive application in spintronics, and in particular the perpendicular magnetic anisotropy characteristic of Co−Fe−B−MgO systems is of great interest. While some efforts have been made to examine the effect of composition on magnetic properties of Co−Fe−B materials, the magnetic-property–composition relationship for the Co−Fe−B−MgO system is still not fully understood. Therefore, it is fundamentally and practically important to understand the Co−Fe−B composition dependence of the magnetic properties of Co−Fe−B−MgO systems. This work focuses on the data-storing free layer of double-barrier magnetic tunnel junctions with perpendicular magnetic anisotropy (PMTJs), which include (CoxFe1−x)80B20 ultrathin films sandwiched between two MgO layers and a W insert layer. We study magnetic properties of various (CoxFe1−x)80B20 compositions at different annealing conditions and find x ∼ 35% to have the highest anisotropy energy to ensure high thermal stability, while maintaining the lowest Gilbert damping parameter which is essential to achieve a low critical switching current. This composition also shows the highest thermal stability at elevated temperatures. In addition, we perform first-principle calculations to explain the anomalous composition trends of the magnetization and Gilbert damping parameter. Moreover, we find that the conventional Slater-Pauling curve is not applicable, and it is necessary to consider the magnetization’s dependence on the magnetic anisotropy which in turn depends on (CoxFe1−x)80B20 composition and the oxide interface. Our results provide a perspective for a better understanding of metal-oxide systems with desirable properties for DBL PMTJ applications.