[21a-P02-1~50] 10 スピントロニクス・マグネティクス(ポスター)

[21a-P02-11] 歳差キャップ層を備えたX nm世代のL1₀-FePd/グラフェン記録層のマイクロマグネティクスシミュレーション

〇永沼 博¹ (1.東北大)

キーワード：MRAM、マイクロマグネティクスシミュレーション、グラフェン

Micromagnetic simulation with string method has been calculated for the L1₀-FePd/graphene (L1₀-FePd/Gr) bilayer, and systematically investigated the influence of (1) critical contact diameter (CD), (2) thicknesses (t), (3) interfacial perpendicular magnetic anisotropy (IPMA), and (4) in-plane magnetized precessional capping layer (PCL) on the thermal stability factor (Δ) and current-induced magnetization switching (CIMS). It has been experimentally confirmed that the heterogeneous crystal interface between hexagonal graphene and tetragonal L1₀-FePd is bonded by van der Waals (vdW) force and induces robust IPMA. In this study, we clarify by simulation the potential of an L1₀-FePd/Gr bilayer with PCL for the X-nm-generation as a recording layer of magnetic tunnel junctions (MTJ) for magnetic random-access memory (MRAM), focusing on data retention and writing characteristics. The L1₀-FePd/Gr bilayer has enough Δ for 10-year retention in the CD of 7 nm with a thickness of 3 nm. The Δ was increased 7% (CD = 7 nm) and 10% (CD = 10 nm) by IPMA between the L1₀-FePd and the graphene. The PCL layer is assumed a low anisotropy having an in-plane magnetization resulting in the low excitation voltage for precession. The square single pulse with 1.5 V and 5 nsec is used. The PCL shortens the incubation time for the CIMS by more than 50% in the case of the L1₀-FePd/Gr bilayer. The reduction of incubation time is mainly attributed to the exchange coupling between L1₀-FePd/Gr and PCL. From the viewpoint of retention and switching properties, the L1₀-FePd/Gr bilayer recording layer with PCL has potential in X-nm generation ultra-high-density MRAM.