Engineering Interfacial Perpendicular Magnetic Anisotropy in Fe₂CoSi/Pt Multilayers with Interfacial Strain and Orbital Hybridization

Abstract

We report a large interfacial perpendicular magnetic anisotropy (PMA) in [Fe2CoSi/Pt] n (FCS/Pt) multilayers deposited on thermally oxidized Si substrates. A maximum anisotropy energy density, K u, of 2.64 Merg/cm3 is achieved with an optimized stack. We are able to tune the PMA by adjusting the Pt and FCS film thicknesses and number of periods of the multilayer structure, as these significantly affect the lattice structure of FCS/Pt stack. Both high-resolution transmission electron microscopy and structural relaxation of the atomistic model using first-principles calculations reveal that while the multilayer structure assumes a monoclinic structure (α = 84°), the FCS films undergo a local orthorhombic distortion from the bulk structure due to the strain imposed by the FCS/Pt interface. By analyzing the orbital-resolved density of states of the system, we propose that both the orthorhombic distortion of the FCS and orbital interactions between interface Pt and Fe atoms are responsible for the high PMA. For the first time, a large interfacial PMA is demonstrated in the Fe-based Heusler/Pt multilayer structure with underlying mechanisms discussed via both experiments and first-principles calculations. Thus, we have shown that there is great potential in strain-enhanced FCS/Pt multilayers in future applications in spintronic devices.

Chirality-Induced Noncollinear Magnetization and Asymmetric Domain-Wall Propagation in Hydrogenated CoPd Thin Films

“…Strong PMOKE signals shown in Figure h indicate prominent perpendicular magnetization after hydrogen exposure and evacuation. It has been found in our previous study that the magnetic anisotropy is dominated by PMA for CoPd films with thicknesses of ≲10 nm, which can be attributed to the tetragonal L 1 0 ordering in the CoPd alloy − even on the short-range scale, , and to the interfacial anisotropy or strain. − Oxidation diminishes PMA, but hydrogenation afterward can enhance PMA with proper hydrogen concentrations. ,− The perpendicular magnetization under in-plane fields after hydrogenation can be attributed to the PMA and the long-range coupling induced by hydrogenation that modulates the electronic structure and orbital moments of the alloy atoms. Indirect exchange coupling of Co magnetic moments is established via the conduction electrons of Pd between Co atoms, and the uptake of hydrogen changes the electronic structure of Pd and accordingly the interaction.…”

Chirality-Induced Noncollinear Magnetization and Asymmetric Domain-Wall Propagation in Hydrogenated CoPd Thin Films

“…39 The hysteresis loops in the top figures which can be attributed to the tetragonal L1 0 ordering in the CoPd alloy [51][52][53] even on the short-range scale, 53,54 and to the interfacial anisotropy or strain. [55][56][57][58][59][60] Oxidation diminishes PMA, 36 but hydrogenation afterward can enhance PMA with proper hydrogen concentrations. 47,[61][62][63][64][65] The perpendicular magnetization under in-plane fields after hydrogenation can be attributed to the PMA and the long-range coupling 46 The light rectangle in Fig.…”

Origin and Large Enhancement of Large Spin Hall Angle in Weyl Semimetals LaAl$X$ ($X$=Si, Ge)

“…However, the spintronics application is restricted by the magnetic materials and magnetic fields. Spin-orbitronics is a new emerging direction of spintronics, which exploits the relativistic spin-orbit coupling (SOC), and opens fascinating new roads for spin devices made of nonmagnetic materials and operated without magnetic fields [4][5][6][7][8][9][10] .…”

“…The efficiency of such conversion is measured by a parameter of the spin Hall angle (SHA, or θ SH ) 12,16,17 . A direct application of charge-spin conversion is the spin-orbit torque, which utilizes the SHE to provides an ultra-fast and energy-efficient means to switch magnetization of the ferromagnets (FM) in FM/heavy-transition-metal heterostructures 7,10,11,14,18,19 . Spin-orbit torque is of fundamental and technical importance for next-generation devices, and has been widely investigated, such as magnetic random access memories and spin logic devices 20 .…”