Abstract:We report on the static and dynamic magnetic properties of W/CoFeB/Ta/CoFeB/MgO stacks, where the CoFeB layer is split in two by a 0.3 nm-thick Ta "dusting" layer. A total CoFeB thickness between 1.2 and 2.4 nm is studied. Perpendicular magnetic anisotropy is obtained for thickness below 1.8 nm even at the as-deposited stacks, and it is enhanced after annealing. Saturation magnetization is 1520 (1440) kA/m before (after) annealing, increased compared to non-split CoFeB layers. Ferromagnetic resonance measureme… Show more
“…At a series of fixed frequencies, we extract the resonance field and resonance linewidth for the optic and acoustic modes, respectively. We fit the resonance frequency ( f ) vs out-of-plane resonance field ( H ) to the linear Kittel dispersion appropriate for a uniaxial magnetic thin film in an applied perpendicular field: where is the gyromagnetic ratio, where g is the spectroscopic splitting factor, is the Bohr magneton and h is Planck’s constant, is the effective perpendicular magnetic anisotropy 43 , is the vacuum permeability and the optic mode is offset by the interlayer exchange field . Figure 3 ( a ) Example lineshape of SAF A showing optic and acoustic resonance modes at f = 24 GHz; ( b ) temperature dependence of the effective perpendicular anisotropy and interlayer exchange coupling; and ( c ) temperature dependence of the Gilbert damping and inhomogeneous line broadening.…”
Thin ferromagnetic films possessing perpendicular magnetic anisotropy derived from the crystal lattice can deliver the requisite magnetocrystalline anisotropy density for thermally stable magnetic memory and logic devices at the single-digit-nm lateral size. Here, we demonstrate that an epitaxial synthetic antiferromagnet can be formed from L10 FePd, a candidate material with large magnetocrystalline anisotropy energy, through insertion of an ultrathin Ir spacer. Tuning of the Ir spacer thickness leads to synthetic antiferromagnetically coupled FePd layers, with an interlayer exchange field upwards of 0.6 T combined with a perpendicular magnetic anisotropy energy of 0.95 MJ/m3 and a low Gilbert damping of 0.01. Temperature-dependent ferromagnetic resonance measurements show that the Gilbert damping is mostly insensitive to temperature over a range of 20 K up to 300 K. In FePd|Ir|FePd trilayers with lower interlayer exchange coupling, optic and acoustic dynamic ferromagnetic resonance modes are explored as a function of temperature. The ability to engineer low damping and large interlayer exchange coupling in FePd|Ir|FePd synthetic antiferromagnets with high perpendicular magnetic anisotropy could prove useful for high performance spintronic devices.
“…At a series of fixed frequencies, we extract the resonance field and resonance linewidth for the optic and acoustic modes, respectively. We fit the resonance frequency ( f ) vs out-of-plane resonance field ( H ) to the linear Kittel dispersion appropriate for a uniaxial magnetic thin film in an applied perpendicular field: where is the gyromagnetic ratio, where g is the spectroscopic splitting factor, is the Bohr magneton and h is Planck’s constant, is the effective perpendicular magnetic anisotropy 43 , is the vacuum permeability and the optic mode is offset by the interlayer exchange field . Figure 3 ( a ) Example lineshape of SAF A showing optic and acoustic resonance modes at f = 24 GHz; ( b ) temperature dependence of the effective perpendicular anisotropy and interlayer exchange coupling; and ( c ) temperature dependence of the Gilbert damping and inhomogeneous line broadening.…”
Thin ferromagnetic films possessing perpendicular magnetic anisotropy derived from the crystal lattice can deliver the requisite magnetocrystalline anisotropy density for thermally stable magnetic memory and logic devices at the single-digit-nm lateral size. Here, we demonstrate that an epitaxial synthetic antiferromagnet can be formed from L10 FePd, a candidate material with large magnetocrystalline anisotropy energy, through insertion of an ultrathin Ir spacer. Tuning of the Ir spacer thickness leads to synthetic antiferromagnetically coupled FePd layers, with an interlayer exchange field upwards of 0.6 T combined with a perpendicular magnetic anisotropy energy of 0.95 MJ/m3 and a low Gilbert damping of 0.01. Temperature-dependent ferromagnetic resonance measurements show that the Gilbert damping is mostly insensitive to temperature over a range of 20 K up to 300 K. In FePd|Ir|FePd trilayers with lower interlayer exchange coupling, optic and acoustic dynamic ferromagnetic resonance modes are explored as a function of temperature. The ability to engineer low damping and large interlayer exchange coupling in FePd|Ir|FePd synthetic antiferromagnets with high perpendicular magnetic anisotropy could prove useful for high performance spintronic devices.
“…In the field of modern spintronics, high-performance magnetic materials are essential for realizing multiple applications, such as in-memory computing, microwave communication, information perception, etc. 1,2 Transition-metal oxides (TMOs) are the potential candidates due to their abundant functionalities, including colossal magnetoresistance, low damping coefficient, high spin polarization, etc. 3−8 Additionally, they show great tunability in magnetic ordering structures among ferro-, ferri-, and antiferromagnetism coupled with metallicity or insulation.…”
Section: ■ Introductionmentioning
confidence: 99%
“…In the field of modern spintronics, high-performance magnetic materials are essential for realizing multiple applications, such as in-memory computing, microwave communication, information perception, etc. , Transition-metal oxides (TMOs) are the potential candidates due to their abundant functionalities, including colossal magnetoresistance, low damping coefficient, high spin polarization, etc. − Additionally, they show great tunability in magnetic ordering structures among ferro-, ferri-, and antiferromagnetism coupled with metallicity or insulation. − These characteristics offer TMOs the advantage of developing diverse spintronics functionalities. On the other hand, magnets with strong perpendicular magnetic anisotropy (PMA), with typical anisotropy energy ( K U ) above 10 6 erg/cm 3 , have attracted perennial attention because of their advantages of reducing characteristic size while maintaining thermal stability in nanoscaled spintronic devices. − However, weak structural anisotropy and/or the spin–orbit coupling (SOC) effect limit the magnetic crystalline anisotropy (MCA) in most magnetic TMO films, resulting in in-plane magnetic anisotropy (MA) dominated by shape anisotropy. , This restricts the application of TMOs in PMA-based devices.…”
Strong
perpendicular magnetic anisotropy (PMA) is crucial
for high-performance
spintronic devices. However, in transition-metal oxides, it is challenging
to achieve an excellent PMA property (anisotropy energy, K
U > 106 erg/cm3), limiting their
application potential. Here, we report a pathway to achieve obvious
PMA in 3d–5d [nLa0.67Sr0.33MnO3,nSrIrO3]m ([nLSMO, nSIO]m) heterostructures via the cooperation of
interfacial engineering and crystal orientation. By depositing multilayers
with a (110) orientation, significant PMA is observed despite the
fact that the bare LSMO and (001)-oriented heterostructures show in-plane
magnetic anisotropy. First-principles calculations suggest that in
the (110)-oriented heterosystems, SIO exhibits a large and perpendicular
single-ion anisotropy attributed to its strong spin–orbit coupling
effect, which leads to the PMA through strong orbital hybridization
between Mn and Ir ions at the LSMO/SIO interface. By varying thicknesses
(n) of LSMO and SIO, the K
U can be optimized to 4 × 106 erg/cm3.
Moreover, the conductive behavior can also be drastically altered
between insulation and metallicity with the n change,
implying the potential for simultaneously obtaining ferromagnetic
metals and insulators with sizable PMA in one oxide heterosystem.
These findings highlight the importance of interfacial engineering
and crystalline orientation in tuning PMA in oxides and provide a
feasible route for developing high-performance oxide-based spintronic
devices.
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