Shape and strain-induced magnetization reorientation and magnetic anisotropy in thin film Ti/CoCrPt/Ti lines and rings

Abstract

The contributions to the magnetic anisotropy of thin-film rings and lines of width 50 nm and above made from Ti͑5 nm͒ / Co 0.66 Cr 0.22 Pt 0.12 ͑10 and 20 nm͒/Ti ͑3 nm͒ with a perpendicular magnetocrystalline anisotropy are investigated, using magnetic force microscopy to image the ac-demagnetized state. Four regimes of behavior were observed in both lines and rings. Samples with the largest widths ͑Ͼ500 nm͒ showed an out-ofplane maze domain structure typical of unpatterned films with domain widths of ϳ200 nm. As the linewidth decreased, a "bamboo" domain structure forms in which the domain walls lie approximately perpendicular to the linewidth. Further linewidth decreases result in a reorientation to a net in-plane anisotropy perpendicular to the linewidth, and for the narrowest lines, Ͻ200-nm wide, the anisotropy reorients in plane parallel to the line. The evolution of anisotropy is modeled in terms of contributions from magnetocrystalline, shape, and first-and second-order magnetoelastic terms, and good agreement with experiment is obtained, considering both bulk and surface anisotropy contributions.

Domain-wall structure in thin films with perpendicular anisotropy: Magnetic force microscopy and polarized neutron reflectometry study

“…Stripe domains were present, typical of systems with perpendicular magnetic anisotropy. From the self-correlation transform of the MFM image [49], an estimation of the average domain size was ≈(180 ± 10) nm [50]. On the other hand, Fig.…”

Insights into the role of magnetoelastic anisotropy in the magnetization reorientation of magnetic nanowires

“…6(b) shows α(T ) for Ni, Al, and Al 2 O 3 and, although, for T > 200 K, α(T ) exhibits a fairly linear trend, a tendency toward a constant value is seen as we lower the temperature. The upper limit of the temperature-dependent strain [ε(T )] exercised by the Al on the Ni NWs is then given by the mismatch between α Al and α Al 2 O 3 , and can be calculated by 12,13,42 Considering that the NWs are subjected to an in-plane biaxial strain, 43 the axial stress (σ ax ) is then obtained from…”

Microscopic reversal magnetization mechanisms in CoCrPt thin films with perpendicular magnetic anisotropy: Fractal structure versus labyrinth stripe domains

“…In prior works, we showed that the hysteresis loops of both 10-and 20-nm-thick CoCrPt thin films had out-of-plane remanence ratio ≈ 1, and an in-plane hard axis [28,29]. MFM of ac-demagnetized 20-nm-thick CoCrPt films showed a maze domain structure, typical of thin films with out-of-plane anisotropy, and with an average domain size of (180 ± 10) nm [28,30] (the 10-nm film could not be imaged since the stray field of the MFM tip significantly modified the domain patterns). Moreover, using MFM, polarized neutron reflectometry, and micromagnetic simulations, we determined that while the domain walls in 20-nm-thick CoCrPt films consist of a Bloch wall in the center of the thin film with a pair of Néel caps at the surfaces, the 10-nm-thick film exhibits pure Bloch walls [28].…”