Perpendicular magnetic anisotropy and interfacial Dzyaloshinskii–Moriya interaction in as grown and annealed X/Co/Y ultrathin systems

Abstract

The perpendicular magnetic anisotropy (PMA) and the interfacial Dzyaloshinskii-Moriya interaction (iDMI) are investigated in as grown and 300 • C annealed Co-based ultrathin systems. For this, Co films of various thicknesses (0.8 nm t Co 5.7 nm) were deposited by magnetron sputtering on thermally oxidized Si substrates using Pt, W, Ir, Ti, Ru and MgO buffer or/and capping layers. X-ray diffraction was used to investigate their structural properties and vibrating sample magnetometry (VSM) was used to determine the magnetic dead layer thickness and the magnetization at saturation (M s ). VSM revealed that the M s for the Pt and the Ir buffered and capped films is the largest. Microstrip line ferromagnetic resonance (MS-FMR), used to extract the gyromagnetic ratio of the thicker Co films, revealed the existence of a second order PMA term, which is thickness dependent. Brillouin light scattering (BLS) in the Damon-Eshbach configuration was used to investigate the thickness dependence of the iDMI effective constant from the spin wave vector dependence of the frequency difference between Stokes and anti-Stokes lines. BLS and MS-FMR techniques were combined to measure the spin wave frequency variation as a function of the in-plane applied magnetic field (where the second order PMA contribution vanishes). The thickness dependence of the effective magnetization was then deduced and used to investigate PMA. For all the systems, PMA results from interface and volume contributions that we determined. The largest interface PMA constants were obtained for Pt-and Ir-based systems due to the electron hybridization of Co with these heavy metals having high spin orbit coupling. Annealing at 300 • C increases both the interface PMA and iDMI for the Pt/Co/MgO most probably due to de-mixing of interpenetrating oxygen atoms from the Co layer and the formation of a sharp Co/O interface.

Interfacial Dzyaloshinskii–Moriya Interaction, Perpendicular Magnetic Anisotropy, and Damping in CoFeB-/Oxide-Based Systems

“…The perpendicular anisotropy constant (K) is then determined. To have 4Meff, MS-FMR and BLS data, giving the in-plane applied magnetic field dependence of the uniform precession mode frequency (MS-FMR) and mean frequency (FS+FaS)/2, have been fitted using equation (2) reported in [29] and [31], respectively. Note that MS-FMR measurements revealed the existence of small uniaxial in-plane anisotropy, note exceeding 60 Oe.…”

Dzyaloshinskii–Moriya interaction determined from spin wave nonreciprocity and magnetic bubble asymmetry in Pt/Co/Ir/Co/Pt synthetic ferrimagnets

“…Solid lines are theoretical dependences of frequencies of acoustic mode (red line) and optic mode (black line) on interlayer exchange interaction. Point at E ex = 0 was taken from [55] for Pt/Co/Ir monolayer of t Co = 1.07 nm thickness. Typical BLS spectra containing acoustic and optic peaks are presented in the insertions.…”

Nonzero Spontaneous Magnetic Moment along the b-Axis and the 2-Fold Spin Reorientation Transition in a Er0.4Gd0.6FeO3 Single Crystal

“…Rare-earth orthoferrites (RFeO 3 ) have a distorted perovskite structure with a space group of Pbnm . − As a functional material family, RFeO 3 attracts great scientific interest and has technological significance for potential applications such as magneto-optical switch, ultrafast optomagnetic recording, precession excitation induced by terahertz pulses, and magnetism-induced ferroelectric multiferroics. − Their abundant magnetic properties mainly originate from 3d-electrons of Fe 3+ and 4f-electrons of R 3+ . , The two magnetic ions (R 3+ and Fe 3+ ) form in three types of magnetic sublattices, including Fe 3+ –Fe 3+ , Fe 3+ –R 3+ , and R 3+ –R 3+ sublattices . The strongest one of those is Fe 3+ –Fe 3+ with G-type antiferromagnetic interaction, which causes the iron ions to orient opposite to all nearest neighbors in three dimensions below the first Neel temperature at 650–700 K. The presence of a Dzyaloshinskii–Moriya interaction − induces an asymmetric electronic exchange, resulting in a spontaneous magnetization in the c -axis of a RFeO 3 single crystal below the Neel temperature. In RFeO 3 , three well-documented spin configurations are Γ 1 (A x , G y , G z ), Γ 2 (F x , C x , G x ), and Γ 4 (G x , A y , F z ), and the mutual conversion between two different configurations is known as spin reorientation transition (SRT). − It is worth noting that the origin of SRT is distinct for different RFeO 3 , and we generally pay attention to temperature-induced SRT.…”