Dysprosium Iron Garnet Thin Films with Perpendicular Magnetic Anisotropy on Silicon

Abstract

magnetization, [12,13] magnetocrystalline anisotropy, [14] magnetostriction, [15] Gilbert damping parameter, [16-19] and magnetooptical spectral response, [10,20,21] and the net anisotropy may be varied widely by choice of substrate, which affects the strain state of the film. [22,23] Ferrimagnetic insulators, such as YIG and REIG, are particularly promising for spintronics as they do not contribute Ohmic losses from parasitic current shunting and exhibit fast magnetization dynamics and low losses in the THz regime. [24] Films with perpendicular magnetic anisotropy (PMA) are advantageous for investigation of spin-orbit torque (SOT) effects, chiral magnetic textures such as skyrmions, and for high density information storage based on domain walls. [25,26] It is difficult to grow YIG with PMA, but REIG films with PMA have been grown, and manipulation of their magnetization has been demonstrated via a spin-orbit torque (SOT) from an adjacent heavy metal [3,27] or from a topological insulator [28,29] with a large spin Hall angle. Electrical control of the magnetization using the damping-like SOT offers the potential for memory and logic devices with ultra-low power dissipation. [30-32] Taking advantage of these properties in spintronic devices requires the integration of PMA REIG films onto non-garnet substrates; silicon is of particular interest as a substrate due to its commercial ubiquity. Single crystal garnet thin films have been grown with PMA by selecting a substrate and garnet composition such that the out-of-plane magnetoelastic anisotropy K me originating from epitaxial lattice mismatch overcomes the shape anisotropy K sh. PMA has been demonstrated in samarium-, [33] thulium-, [18] europium-, [19,34] and terbium [19,34] iron garnets on gadolinium gallium garnet (Gd 3 Ga 5 O 12 , GGG) substrates, and bismuthsubstituted yttrium-[7] and thulium-[35,36] iron garnets on substituted GGG (Gd 2.6 Ca 0.4 Ga 4.1 Mg 0.25 Zr 0.65 O 12 , SGGG). For films grown on (111)-oriented garnet substrates the magnetocrystalline anisotropy also contributes to PMA by an amount K 1 /12, which is typically small, where K 1 is the first order magnetocrystalline anisotropy coefficient. For polycrystalline films grown on non-garnet substrates, the elastic anisotropy originates instead from thermal expansion mismatch with the substrate on cooling from the annealing Magnetic insulators, such as the rare-earth iron garnets, are promising materials for energy-efficient spintronic memory and logic devices, and their anisotropy, magnetization, and other properties can be tuned over a wide range through selection of the rare-earth ion. Films are typically grown as epitaxial single crystals on garnet substrates, but integration of these materials with conventional electronic devices requires growth on Si. The growth, magnetic, and spin transport properties of polycrystalline films of dysprosium iron garnet (DyIG) with perpendicular magnetic anisotropy (PMA) on Si substrates and as single crystal films on garnet substrates are reported. PMA orig...

Magnetic Properties and Growth‐Induced Anisotropy in Yttrium Thulium Iron Garnet Thin Films

“…[ 10 ] Tuning the magnetic properties of REIG thin films, including the magnetization, anisotropy, coercivity, magnetostriction, compensation temperature and damping, has been investigated through control of the RE ion, the RE:Fe ratio, oxygen content, and substrate strain. [ 11–13 ] In PLD or sputtered garnet films, PMA can be introduced due to magnetoelastic anisotropy, [ 11,13–15 ] and has been controlled through strain engineering by varying the substrate epitaxial mismatch strain [ 11,16 ] or the thermal mismatch strain [ 17,18 ] and by altering the magnetostriction coefficients by fully substituting the RE species on the c ‐site. [ 11,19,20 ] PMA of magnetoelastic origin has also been achieved in strained YIG [ 21 ] and in Bi‐substituted YIG, [ 22 ] which exhibit lower damping than REIGs, and in garnets with multiple substitutions such as (Dy,Ce) 3 (Fe,Al) 5 O 12 .…”

Spin‐Orbit Torque and Interfacial Dzyaloshinskii–Moriya Interaction in Heavy Metal/Ferrimagnetic Insulator Deposited by Magnetron Sputtering

“…Ferrimagnetic insulators (FMIs) have attracted intensive studies for the application in spintronic devices due to their potential advantages. [ 1–23 ] Their low damping property, long spin transmission length, and absence of Ohmic loss ensure high‐speed response and low‐energy consumption in the future memory and logic devices. [ 24–26 ] Moreover, although a current cannot flow in the FMIs, their magnetization can be detected and manipulated electrically in heavy metal (HM)/FMI bilayers.…”

Interfacial and Bulk Magnetic Properties of Stoichiometric Cerium Doped Terbium Iron Garnet Polycrystalline Thin Films

“…Investigations on garnet interfaces have been confined to epitaxial garnet films on gadolinium gallium garnet (GGG). [ 14–16 ] Jakubisova et al attributed the anomaly in MO polar Kerr rotation in nm‐thick yttrium iron garnet (YIG) on GGG (111) to the presence of a transition layer with opposite Fe 3+ sublattice magnetization that is antiferromagnetically coupled to the dodecahedral Gd 3+ in the substrate. [ 17 ] In other research, the formation of a magnetically compensated layer from the interdiffusion of Fe from the film and Gd‐Ga from the substrate is suggested as a result of high temperature annealing.…”