Thick permalloy films for the imaging of spin texture dynamics in perpendicularly magnetized systems

Finizio, Simone; Wintz, Sebastian; Bracher, David; Kirk, E.; Семисалова, А.С.; Förster, Jens; Zeissler, Katharina; Weßels, Teresa; Weigand, Markus; Lenz, K.; Kleibert, Armin; Raabe, Jörg

doi:10.1103/physrevb.98.104415

Cited by 16 publications

(21 citation statements)

References 39 publications

(76 reference statements)

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“…Further, magnetic skyrmions with q = 2 have also been predicted in frustrated 62 and itinerant 63 magnets. An alternative platform to consider would be thick permalloy (Ni 81 Fe 19 ) disks 64 , since the existence of skyrmions with p up to 3 was recently shown in them, although this would require a different setup. High-p skyrmions were also recently observed in Pd/Fe/Ir(111) magnetic islands 65 .…”

Section: Discussionmentioning

confidence: 99%

Topological superconductivity with deformable magnetic skyrmions

2019

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Magnetic skyrmions are nanoscale spin configurations that are efficiently created and manipulated. They hold great promises for next-generation spintronics applications. In parallel, the interplay of magnetism, superconductivity and spin-orbit coupling has proved to be a versatile platform for engineering topological superconductivity predicted to host non-abelian excitations, Majorana zero modes. We show that topological superconductivity can be induced by proximitizing skyrmions and conventional superconductors, without need for additional ingredients. Apart from a previously reported Majorana zero mode in the core of the skyrmion, we find a more universal chiral band of Majorana modes on the edge of the skyrmion. We show that the chiral Majorana band is effectively flat in the physically relevant parameter regime, leading to interesting robustness and scaling properties. In particular, the number of Majorana modes in the (nearly-)flat band scales with the perimeter length of the system, while being robust to local disorder. 1 arXiv:1904.03005v3 [cond-mat.supr-con] 23 Oct 2019 8 where all energies are in units of the bandwidth t, all distances are in units of the lattice spacing a (see Supplementary Note 1 and Supplementary Figure 1 for details). For precisely |m J | = |m * J | the wire is at the topological transition and has a gapless spectrum, giving our model a bulk-gap-closing point as shown in Fig. 2c.The MFB found here has a protection by a chiral symmetry, as MFB's were found to have in models with translational symmetries 39,40,51 . Note that the wire Hamiltonian and its MFB become a correct model for our texture Eq. (1) if we choose q = 0 and thereby nullify the H slope m J (r) term. Physically, this is a special case where instead of the skyrmion shape the texture becomes coplanar (in the xz-plane, see Eq. (1)), and the orthogonal direction provides a chiral operator Ξ = τ y σ ythat anticommutes with the Hamiltonian (see Eq. (2)). Since all the MFB states have the same chirality, they cannot hybridize among themselves. It is difficult to remove the MFB states 51 , namely, a perturbation must have energy larger than the effective gap; or, it should hybridize the MFB with low energy bulk states at |m J | ≈ |m * J |, which are few; or, chirality symmetry must be broken (out-of-xz-plane exchange field). We note that the proof of existence of the MFB rests on the rotational symmetry of the q = 0 coplanar texture, since this symmetry provides the m J quantum number. Consider now deformations of the shape of the edge imposed on our q = 0 coplanar texture. These geometric deformations would generally mix the m J sectors, yet the described stability of the MFB implies that the deformations would be inefficient in removing the MFB states.We can now proceed to the relevant model for a skyrmion with arbitrary q = 0:The single term H slope m J (r) breaks the chiral symmetry Ξ, and there are no other chiral operators. The term H slope m J (r) exactly contributes an energy ε edgestate (m J ) ∼ m J to an MFB state ...

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Section: Discussionmentioning

confidence: 99%

Topological superconductivity with deformable magnetic skyrmions

2019

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“…These values span the typical ranges for experimental samples routinely investigated at the PolLux beamline [i.e. ranging from 0.8 nm-thick Co nanostructures (Baumgartner et al, 2017) to 200 nm-thick Fe x Ni 1-x microstructures (Finizio et al, 2018a)]. In addition to those variables, the following parameters have been kept constant (but can in principle be varied with minimal changes to the simulation script):…”

Section: Monte Carlo Simulationsmentioning

confidence: 99%

Why is my image noisy? A look into the terms contributing to a time-resolved X-ray microscopy image

Finizio¹,

Watts²,

Raabe³

2021

J Synchrotron Rad

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Through Monte Carlo simulations, we investigate how various experimental parameters can influence the quality of time-resolved scanning transmission X-ray microscopy images. In particular, the effect of the X-ray photon flux, of the thickness of the investigated samples, and of the frequency of the dynamical process under investigation on the resulting time-resolved image are investigated. The ideal sample and imaging conditions that allow for an optimal image quality are then identifed.

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“…Finally, it is noteworthy that, for the thickness of the Py film considered here, this perpendicularly magnetized state coexists with an in-plane magnetic vortex state. 57 To achieve a high spatial resolution for such a thin sample, a pixel size of 15 x 15 nm 2 was chosen for a 2 x 2 µm 2 FOV. The calculated beam spot size at the sample was about 43 nm (see SI), however, in order to oversample in the scan and in the angles and to ensure sufficient spatial resolution, a total number of projections N = 79 was recorded using the Bloch domain walls at the center of the disc can be seen in (C), which is a virtual cut at the height shown with a dotted line in the cross section of (A).…”

Section: This Work Reports On Soxl and The New Instrumentation For Realizing This New Techniquementioning

confidence: 99%

From 2D STXM to 3D Imaging: Soft X-ray Laminography of Thin Specimens

et al. 2020

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X-ray tomography has become an indispensable tool for studying complex 3D interior structures with high spatial resolution. 3D imaging using soft X-rays offers powerful contrast mechanisms, but has seen limited success with tomography due to the restrictions imposed by the much lower energy of the probe beam. The generalized geometry of laminography, characterized by a tilted axis of rotation, provides nm-scale 3D resolution for the investigation of extended (mm range) but thin (µm to

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Thick permalloy films for the imaging of spin texture dynamics in perpendicularly magnetized systems

Cited by 16 publications

References 39 publications

Topological superconductivity with deformable magnetic skyrmions

Topological superconductivity with deformable magnetic skyrmions

Why is my image noisy? A look into the terms contributing to a time-resolved X-ray microscopy image

From 2D STXM to 3D Imaging: Soft X-ray Laminography of Thin Specimens

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