Magnetic domain patterns in Co2MnGe Heusler nanostripes

Abstract

We have prepared thin films of the ferromagnetic Heusler alloy Co 2 MnGe on a-plane Al 2 O 3 substrates exhibiting growth-induced, superimposed fourfold and uniaxial magnetic anisotropies, the symmetry being determined by the single-crystalline Al 2 O 3 substrate. The magnitude of the uniaxial anisotropy compared to the cubic anisotropy can be tuned over a wide range by the film thickness and the growth conditions. On submicrometer-wide stripes of Co 2 MnGe prepared by electron beam lithography we studied magnetic domain patterns by magnetic force microscopy. For stripes with a sufficiently large uniaxial anisotropy and with the easy axis oriented perpendicular to the stripe axis, we find perfectly regular domain patterns with the magnetization direction perpendicular to the stripe axis and alternating from domain to domain. The highly regular and controllable domain patterns in Co 2 MnGe nanostripes could be useful for magnetic storage devices and applications related to spin transfer torque.

Two-magnon scattering by domain wall induced coupling in Co2MnGe/Au/Py layer systems

“…The ability to synthesize perfectly regular domain patterns in the F layer, as was shown in Ref. () for microstructured Heusler alloy thin films, can lead to a periodic DW stray field distribution within the MC. These periodic stray fields may, in turn, allow a control over the DW coupling and concomitantly over the frequency dispersion of spin wave excitations in MC.…”

Strain Anisotropy and Magnetic Domains in Embedded Nanomagnets

“…The periodicity of the domains is determined by the relative magnitudes of the anisotropy energies, imparting a degree of control over the periodicity. Experimentally, such periodic domains have been observed in micrometer‐sized magnetic structures …”

Domain wall dynamics of periodic magnetic domain patterns in Co2MnGe-Heusler microstripes

“…Thin films: angular dependence of the coercivity Prior to lateral patterning, the Co 2 MnGe thin films were magnetically characterized by rotational MOKE technique to determine the in-plane magnetic anisotropy. As previously reported, the effective in-plane magnetic anisotropy for Co 2 MnGe thin films grown on a-plane Al 2 O 3 can be described by a superposition of a fourfold and a uniaxial anisotropy term [29]. The magnitude of the twofold and fourfold anisotropy constants depends on the growth conditions and can vary appreciably.…”

“…Prior to recording the images at zero field, the stripes were magnetically saturated along the magnetic easy axis. In the case of the sample A with dominant in-plane uniaxial anisotropy, competing magnetostatic, magnetocrystalline and exchange interactions result in a regularly symmetric stripe domain configuration with a well-defined domain size [29]. Domains with the magnetization direction perpendicular to the stripe long axis are mostly separated by 180°t ransverse DWs.…”

“…When grown as thin film it often exhibits a growth-induced moderate uniaxial magnetic anisotropy (K U ) superimposed on an anisotropy with cubic symmetry (K 4 ) [23][24][25][26][27][28]. By an adequate choice of thickness, substrate and deposition temperature, thin films with a dominant uniaxial anisotropy or dominant cubic anisotropy can be obtained [26][27][28][29]. The moderate in-plane anisotropy allows for the formation of well-defined periodic domain patterns by the proper combination with the shape anisotropy, while low damping favors the DW motion in such domain structures.…”