Advanced magneto-optical Kerr effect measurements of superconductors at low temperatures

Stahl, Claudia; Gräfe, Joachim; Ruoß, Stephen; Zahn, Patrick; Bayer, Jonas; Simmendinger, Julian; Schütz, Gisela; Albrecht, J.

doi:10.1063/1.4985044

Cited by 4 publications

(3 citation statements)

References 20 publications

(26 reference statements)

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“…In the following we assume that the ferromagnet solely interacts with the superconductor via magnetic dipolar coupling [25][26][27]. The complex interaction in SC/FM compounds is discussed in more details by Stahl et al [28,29].…”

mentioning

confidence: 99%

Magnetic flux penetration into micron-sized superconductor/ferromagnet bilayers

Simmendinger

Weigand

Schütz

et al. 2020

Supercond. Sci. Technol.

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Flux penetration into small superconductor/ferromagnet elements is investigated by magneto-optical imaging and magnetic scanning transmission x-ray microscopy at low temperatures. It is found that penetration of magnetic flux into a thin bilayer of YBCO and Py strongly depends on the direction of a perpendicular magnetic field. The soft-magnetic layer acts as an amplifier for magnetic in-plane components that are generated by electric currents in the superconductor. These in-plane components point in opposite direction above the ferromagnet and below the superconductor. As a consequence a strong inclination of the local magnetic field occurs that significantly slows down or speeds up the flux penetration into such elements. From detailed magnetic scanning x-ray microscopy results it is found that the effect dramatically increases if the elements get smaller. In 20 × 20 μm2 superconducting squares we observe magnetic flux penetration that differs by more than a factor of four when reversing the external magnetic field.

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confidence: 99%

Magnetic flux penetration into micron-sized superconductor/ferromagnet bilayers

Simmendinger

Weigand

Schütz

et al. 2020

Supercond. Sci. Technol.

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“…However, a method for creating and stabilizing complex spin textures, applicable to a large variety of compounds, is yet missing. Recently, a new approach based in the use of hybrid superconductor/ferromagnet (SC/FM) microstructures has demonstrated the possibility to generate and control swirling spin textures − with some degree of stability even above the superconducting transition temperature. , …”

Section: Introductionmentioning

confidence: 99%

Size-Dependence and High Temperature Stability of Radial Vortex Magnetic Textures Imprinted by Superconductor Stray Fields

Sanchez-Manzano,

Orfila,

Sander

et al. 2024

ACS Appl. Mater. Interfaces

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Swirling spin textures, including topologically nontrivial states, such as skyrmions, chiral domain walls, and magnetic vortices, have garnered significant attention within the scientific community due to their appeal from both fundamental and applied points of view. However, their creation, controlled manipulation, and stability are typically constrained to certain systems with specific crystallographic symmetries, bulk or interface interactions, and/or a precise stacking sequence of materials. Recently, a new approach has shown potential for the imprint of magnetic radial vortices in soft ferromagnetic compounds making use of the stray field of YBa 2 Cu 3 O 7-δ superconducting microstructures in ferromagnet/superconductor (FM/SC) hybrids at temperatures below the superconducting transition temperature (T C ). Here, we explore the lower size limit for the imprint of magnetic radial vortices in square and disc shaped structures as well as the persistence of these spin textures above T C , with magnetic domains retaining partial memory. Structures with circular geometry and with FM patterned to smaller radius than the superconductor island facilitate the imprinting of magnetic radial vortices and improve their stability above T C , in contrast to square structures where the presence of magnetic domains increases the dipolar energy. Micromagnetic modeling coupled with a SC field model reveals that the stabilization mechanism above T C is mediated by microstructural defects. Superconducting control of swirling spin textures, and their stabilization above the superconducting transition temperature by means of defect engineering holds promising prospects for shaping superconducting spintronics based on magnetic textures.

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“…Thus, to avoid proximity effects [19] a thin insulating layer is introduced at the SC/FM interface [20], whereby the SC/FM interaction is governed by dipolar coupling [17,18]. As of today, numerous ferromagnetic materials have been used as sensor layers for magnetic imaging, such as thin films of amorphous Co 40 Fe 40 B 20 [21][22][23] Fe 20 Ni 80 (permalloy, Py) [8,17] or epitaxial La 2/3 Ca 1/3 MnO 3 (LCMO) [24].…”

Section: Introductionmentioning

confidence: 99%

Soft-magnetic coatings as possible sensors for magnetic imaging of superconductors

Ionescu

Simmendinger

Bihler

et al. 2019

Supercond. Sci. Technol.

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Magnetic imaging of superconductors typically requires a soft-magnetic material placed on top of the superconductor to probe local magnetic fields. For reasonable results the influence of the magnet onto the superconductor has to be small. Thin YBCO films with soft-magnetic coatings are investigated using SQUID magnetometry. Detailed measurements of the magnetic moment as a function of temperature, magnetic field and time have been performed for different heterostructures. It is found that the modification of the superconducting transport in these heterostructures strongly depends on the magnetic and structural properties of the soft-magnetic material. This effect is especially pronounced for an inhomogeneous coating consisting of ferromagnetic nanoparticles.

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Advanced magneto-optical Kerr effect measurements of superconductors at low temperatures

Abstract: Application of magneto-optical Kerr effect to first-order reversal curve measurements Review of Scientific Instruments 85, 023901 (2014); https://doi

Cited by 4 publications

References 20 publications

Magnetic flux penetration into micron-sized superconductor/ferromagnet bilayers

Magnetic flux penetration into micron-sized superconductor/ferromagnet bilayers

Size-Dependence and High Temperature Stability of Radial Vortex Magnetic Textures Imprinted by Superconductor Stray Fields

Soft-magnetic coatings as possible sensors for magnetic imaging of superconductors

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