[24p-E202-9~17] 10.3 スピンデバイス・磁気メモリ・ストレージ技術

▼ [24p-E202-9] First Principles Studies on the Effect of Grain Boundaries in MgO on Interfacial Perpendicular Magnetic Anisotropy Energy at Fe/MgO Interface in STT-MRAM

〇Keisuke Morishita¹、Yosuke Harashima²、Masaaki Araidai^1,3、Tetsuo Endoh^4,5,6、Kenji Shiraishi^1,3,4 (1.Nagoya Univ.、2.NAIST、3.IMass、4.CIES、5.Tohoku Univ.、6.RIEC)

キーワード：first-principles calculation, interfacial perpendicular magnetic anisotropy

STT-MRAM (spin transfer torque magnetic RAM) has excellent features such as high speed accessibility, high integrated and nonvolatility. Therefore, it is expected to replace volatile memories used as cashe memory and main memory. Nonvolatility of STT-MRAM depends on MTJ (magnetic tunnel junctions) with iPMA (interfacial perpendicular magnetic anisotropy). A strong iPMA is an important factor to obtain a high enough thermal stability, and this iPMA strongly depends on Fe/MgO interface structures. Bean et. al mainly found two kinds of grain boundaries in MgO layer at CoFeB/MgO/CoFeB MTJ. We focus on Σ5(210)[001] symmetric tilt grain boundary and investigate the effect on iPMA by the first-principles calculations using Fe/MgO/Fe model interface, as the collapse of hybridization between d orbitals of interfacial Fe atoms and the second lalyer Fe atoms near GB is cause of decline in iPMA. We suggest that the important factor of iPMA is the d orbital hybridization around Fe atoms as well as well-known interfacial Fe-O bonds.