[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-P02-8] 第一原理計算によるねじれたL1₀-FePd/グラフェン界面におけるXASおよびXMCDスペクトルの解釈

〇永沼 博^1,2,3、植本 光治⁴、安達 隼人⁴、新屋 ひかり⁵、望月 出海⁶、平田 秋彦⁷、Bruno Dlubak⁸、小野 倫也⁴、Pierre Seneor^8,9,2、雨宮 健太⁶ (1.東北大CIES、2.東北大CSIS、3.東北大工、4.神戸大工、5.東北大通研、6.高エネ研物工、7.早稲田理工、8.CNRS/Thales、9.Univ.Paris-Sac.)

キーワード：グラフェン、L10-規則合金、モアレ干渉

The heterogeneous crystal interface of hexagonal graphene and tetragonal L1₀-FePd ordered alloy are bonded by van der Waals forces. In our previous study, we presented [22p-P02-2, in JSAP, 2021] that a robust interfacial perpendicular magnetic anisotropy was excited at the L1₀-FePd/graphene interface (H. Naganuma et al, ACS Nano, 2022). This study focused on the chemical bonding and magnetic properties of the graphene at the L1₀-FePd/ graphene interface. X-ray absorption (XAS) by different angles showed that the π* orbital peak was observed not only at a nominal incident angle (q_NI = 90°) but also at a glance incident angle (q_GI = 30°). From the first-principles calculation, the π* orbital peak observed at a tilted angle (q_GI = 30°) is attributed to the strong chemical bonding of Fe in FePd and C in graphene owing to the close location of the p_z orbital of C and d_z orbital of Fe orbital at the fermi level. The p_z orbital of the π* bonding in C twists into the xy plane direction owing to the chemical bonding with the Fe or the perturbation of the Fe ion to the carbon orbital which is the reason for the twisted interface bonding and the wavy graphene. From the simulation of scanning transmission electron microscopy (STEM), moiré-like contrast was observed between Fe in L1₀-FePd and graphene owing to the twisted interface and periodic displacement of C in graphene. In other words, the twisted and periodic displacement can be experimentally observed with STEM images but not with angular XAS. The X-ray magnetic dichroism (XMCD) spectrum of C in graphene did not show an obvious magnetic moment. It can be interpreted by the first-principles calculation that the XMCD signal was not observed because only the spin moment, not the orbital moment, was induced in the C in graphene.