Surface magnetization and the role of pattern defects in various types of ripple patterned films

Colino, J.; Arranz, Miguel A.; Barbero, Antonio J.; Bollero, A.; Camarero, Julio

doi:10.1088/0022-3727/49/13/135002

Cited by 15 publications

(14 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This large discrepancy can be understood in terms of several factors: i) with increasing film thickness the surface topography of the film is expected to get smeared out resulting in decrease in the modulation depth h, ii) the actual surface/interface contour of the film deviates from an ideal sinusoidal shape in terms of various defects like height corrugation and breaks of continuity along the ripple direction and overlapping ripples and defects like pattern dislocation. 8 In conclusion, evolution of magnetic anisotropy of cobalt film deposited at normal incident on nanopatterned silicon substrate has been studied with increasing film thickness. In-situ MOKE measurements during film deposition allowed us to follow the magnetization behaviour with film thickness, keeping all the other parameters like surface topology and deposition conditions identical.…”

mentioning

confidence: 93%

Evolution of magnetic anisotropy in cobalt film on nanopatterned silicon substrate studied in situ using MOKE

Bukharia

Karmakar

Kumar

et al. 2020

Journal of Magnetism and Magnetic Materials

View full text Add to dashboard Cite

Evolution of magnetization behaviour of cobalt film on nano patterned silicon substrate, with film thickness, has been studied. In situ magneto-optical Kerr effect measurements during film deposition allowed us to study genuine thickness dependence of magnetization behaviour, all other parameters like surface topology, deposition conditions remaining invariant. The film exhibits uniaxial magnetic anisotropy, with its magnitude decreasing with increasing film thickness. Analysis shows that anisotropy has contributions from both, i) exchange energy which is volume dependent and, ii) stray dipolar fields at the surface/interface. This suggests that local magnetization follows only partially the topology of the rippled surface. As expected from energy considerations, for small film thickness, the local magnetization closely follows the surface contour of the ripples making the volume term as the dominant contribution. With increasing film thickness, the local magnetization gradually deviates from the local slope and approaches towards a uniform magnetization along the macroscopic film plane making the surface term as the dominant contribution. Significant deviation from the anisotropy energy expected on the basis of theoretical considerations can be attributed to several factors like, deviation of surface topology from an ideal sinusoidal wave, breaks of continuity along the ripple direction, defects like pattern dislocations, and possible decrease in surface modulation depth with increasing film thickness.

show abstract

mentioning

confidence: 93%

Evolution of magnetic anisotropy in cobalt film on nanopatterned silicon substrate studied in situ using MOKE

Bukharia

Karmakar

Kumar

et al. 2020

Journal of Magnetism and Magnetic Materials

View full text Add to dashboard Cite

show abstract

“…This study also demonstrates that nucleation processes governing magnetization reversal is at the heart of coercivity enhancement, which is the path for the development of high performance permanent magnets 38 , as well as it explains why the SW model can describe successfully the angular-dependence properties of more complex extended systems, i.e., exchange biased ferromagnetic/antiferromagnetic bilayers 39 – 42 and ripple patterned films 43 , where nucleative processes are much more relevant even in quasi-static conditions. This study emphasizes the importance of dynamical effects in order to understand and control magnetic systems.…”

Section: Introductionmentioning

confidence: 57%

Emergence of the Stoner-Wohlfarth astroid in thin films at dynamic regime

Cuñado

Bollero

Pérez-Castañeda

et al. 2017

Sci Rep

View full text Add to dashboard Cite

The Stoner-Wohlfarth (SW) model is the simplest model that describes adequately the magnetization reversal of nanoscale systems that are small enough to contain single magnetic domains. However for larger sizes where multi-domain effects are present, e.g., in thin films, this simple macrospin approximation fails and the experimental critical curve, referred as SW astroid, is far from its predictions. Here we show that this discrepancy could vanish also in extended system. We present a detailed angular-dependent study of magnetization reversal dynamics of a thin film with well-defined uniaxial magnetic anisotropy, performed over 9 decades of applied field sweep rate (dH/dt). The angular-dependent properties display a gradual transition from domain wall pinning and motion-like behaviour to a nucleative single-particle one, as dH/dt increases. Remarkably, in the high dynamic regime, where nucleation of reversed domains is the dominant mechanism of the magnetization reversal (nucleative regime), the magnetic properties including the astroid become closer to the ones predicted by SW model. The results also show why the SW model can successfully describe other extended systems that present nucleative regime, even in quasi-static conditions.

show abstract

“…As commented above, in the vicinity of the HA, the Voigt effect is basically ∝ M 2 ⊥ and we could outline an expected behaviour of M ⊥ under the applied H around HA. In spite of the quadratic dependence of δ V on H, that simulation could help us to visualize the M ⊥ reversal perpendicular to the anisotropy axis (Φ = 0), similarly to vectorial Kerr measurements in nanostructured Co films [15,29]. These modelized cycles can be seen in the insets of Fig.…”

Section: Magnetic Birefringencementioning

confidence: 81%

“…After deposition, the magnetic thin film grown on that ripples array reproduces the same spatial pattern, showing a coincident anisotropy axis parallel to the ripples direction. Thus, in this corrugated Permalloy film, two different sources rule the M reversal in such anisotropic system, on one hand, the nucleation and growth of 180 • magnetic domains along the ripple direction (easy magnetic axis, EA), on the other hand, the coherent rotation of M perpendicular to the ripple direction (hard magnetic, HA) [15,29]. The existence of these unlike mechanisms to switch M consequently affects the linear polarized light transmitting across the sample, yielding the occurrence of two intensity peaks centered above the coercive field, H C , values [28,30].…”

Section: Magnetic Birefringencementioning

confidence: 99%

Form and magnetic birefringence in undulated Permalloy/PET films

et al. 2019

View full text Add to dashboard Cite

We report the measurement of form and magnetic birefringence in Permalloy (Ni80Fe20) films grown on rippled Poly(Ethylene Terephthalate), PET, substrates. Prior to Permalloy deposition, Laser Induced Periodic Surface Structures (LIPSS) were generated on the polymeric substrate by a nanosecond laser beam, developing an ordered rippled nanostructure. Due to their high transparency factor, we could investigate the behavior of linear polarized light transmitting at normal incidence on Permalloy/PET sample. The results show the existence of an optical axis parallel to the ripples direction, which yields an strong form birefringence effect arising from the laser patterning. Concerning the Permalloy thin film, the study of its in-plane magnetization was carried out measuring the Voigt magnetooptical effect. The obtained data in our samples reveal the appearance of two different mechanisms to reverse the magnetization, as the external magnetic field is parallel or perpendicular to the ripples direction. Accordingly, the transmitted light shows a magnetic birefringence depending on the relative orientation between the ripple direction, i.e. the optical axis of the LIPSS, and the in-plane magnetization of the Permalloy film.

show abstract

Surface magnetization and the role of pattern defects in various types of ripple patterned films

Cited by 15 publications

References 32 publications

Evolution of magnetic anisotropy in cobalt film on nanopatterned silicon substrate studied in situ using MOKE

Evolution of magnetic anisotropy in cobalt film on nanopatterned silicon substrate studied in situ using MOKE

Emergence of the Stoner-Wohlfarth astroid in thin films at dynamic regime

Form and magnetic birefringence in undulated Permalloy/PET films

Contact Info

Product

Resources

About