Quantitative magneto-optical investigation of superconductor/ferromagnet hybrid structures

Shaw, Gorky; Brisbois, Jérémy; Pinheiro, Lincoln Brum de Leite Gusmão; Müller, Jonas; Alvarez, Sylvain Blanco; Devillers, Thibaut; Dempsey, Nora; Scheerder, Jeroen; Vondel, J. Van de; Melinte, Sorin; Vanderbemden, Philippe; Motta, M.; Ortiz, W.A.; Hasselbach, K.; Kramer, R. B. G.; Silhanek, Alejandro

doi:10.1063/1.5016293

Cited by 28 publications

(21 citation statements)

References 70 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…More information about the MO imaging setup can be found in ref. 22 . Low temperature MO measurements are performed in a closed-cycle cryostat and the external magnetic field was applied through a copper coil with resistance R = 22.1 Ω and inductance L = 26 mH.…”

Section: Methodsmentioning

confidence: 99%

“…Low temperature MO measurements are performed in a closed-cycle cryostat and the external magnetic field was applied through a copper coil with resistance R = 22.1 Ω and inductance L = 26 mH. MO imaging allows for the detection of small magnetic field changes 22 (~10 μ T). This value is to be compared with the smallest magnetization change 50 μ T picked up by a superconducting quantum interference device (SQUID) with typical sensitivity of 10 −8 emu, on the entire sample 23 .…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Statistics of thermomagnetic breakdown in Nb superconducting films

Alvarez¹,

Brisbois²,

Melinte³

et al. 2019

Sci Rep

Self Cite

View full text Add to dashboard Cite

Superconductors are well known for their ability to screen out magnetic fields. In type-II superconductors, as the magnetic field pressure is progressively increased, magnetic flux accumulates at the periphery of the sample, very much like charges accumulate in a capacitor when voltage is increased. As for capacitors, exceeding certain threshold field causes the blocked magnetic flux to abruptly penetrate into the sample. This phenomenon, triggered by a thermomagnetic instability, is somewhat analogous to the dielectric breakdown of the capacitor and leaves behind a similar Lichtenberg imprinting. Even though electrical breakdown threshold has been extensively studied in dielectrics, little information is known about the statistical distribution of the thermomagnetic breakdown in superconductors. In this work, we address this problem by performing magneto-optical imaging experiments on a Nb film where nanometric heating elements are used to rapidly erase the magnetic history of the sample. We demonstrate that the size and shape distributions of avalanches permits to unambiguously identify the transition between two regimes where either thermal diffusivity or magnetic diffusivity dominates. Clear criteria for discriminating athermal dynamic avalanches from thermally driven avalanches are introduced. This allows us to provide the first precise determination of the threshold field of the thermomagnetic breakdown and unveil the details of the transition from finger-like magnetic burst to dendritic branching morphology. These findings open a new avenue in the interdisciplinary exploration of catastrophic avalanches through non destructive repeatable experiments.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Statistics of thermomagnetic breakdown in Nb superconducting films

Alvarez¹,

Brisbois²,

Melinte³

et al. 2019

Sci Rep

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, since the stepped sample surface made it difficult to have the indicator in close proximity to the whole sample surface, this value should be considered with some caution. Indeed, the actual T c could be slightly underestimated since the magnetic signal, weakened when the indicator-to-sample gap is increased [31], could be buried in noise before the transition to the normal state takes place. Figure 3 summarizes the temperature dependence of the in-plane electrical resistivity at different applied fields.…”

Section: Methodsmentioning

confidence: 99%

Upper critical fields in Ba2Ti2Fe2As4O single crystals: Evidence for dominant Pauli paramagnetic effect

et al. 2018

Self Cite

View full text Add to dashboard Cite

We report on magneto-optical imaging and the temperature dependency of the upper critical fields H c c2 (T ) parallel to the c axis and H ab c2 (T ) parallel to the ab plane in Ba 2 Ti 2 Fe 2 As 4 O single crystals. These data were inferred from the measurements of the temperature-dependent resistance in static magnetic fields up to 14 T and magnetoresistance in pulsed fields up to 60 T. H c2 values are found to be 52 and 50 T for H ab and H c, respectively. These values are 1.2-1.35 times larger than the weak-coupling Pauli paramagnetic limit (H p ∼ 1.84T c ), indicating that enhanced paramagnetic limiting is essential and this superconductor is unconventional. Our observations of strong bending in the H ab c2 (T ) curves and a nearly isotropic maximum upper critical field H ab c2 (0) ≈ H c c2 (0) support the presence of a strong Pauli paramagnetic effect. We show that the Werthamer-Helfand-Hohenberg (WHH) formula that includes the spin-orbit scattering can effectively describe the H ab c2 (T ) curve, whereas H c2 deviates from the conventional WHH theoretical model without considering the spin paramagnetic effect for the H c and H ab directions. For H c, a two-band model is required to fully reproduce the behavior of H c2 , while for H ab the spin paramagnetic effect is responsible for the behavior of H c2 . The anisotropy of H c2 is close to 3 near T c and decreases rapidly at lower temperatures.

show abstract

“…A number of such Py/Nb heterostructures were prepared, with different thicknesses of the Py layer (t = 50 nm, 100 nm, and 460 nm). The heterostructures were investigated primarily using MOI (see Reference [72] for more details on the MOI setup). The magnetic landscape in these samples has been found to be highly re-configurable by imprinting flexible micromagnet structures for guidance of flux penetration in a superconductor [56,72].…”

Section: Observation Of Imprinted Flux Trajectories In Permalloy Usinmentioning

confidence: 99%

Magnetic Recording of Superconducting States

Shaw

Alvarez

Brisbois

et al. 2019

Metals

Self Cite

View full text Add to dashboard Cite

Local polarization of magnetic materials has become a well-known and widely used method for storing binary information. Numerous applications in our daily life such as credit cards, computer hard drives, and the popular magnetic drawing board toy, rely on this principle. In this work, we review the recent advances on the magnetic recording of inhomogeneous magnetic landscapes produced by superconducting films. We summarize the current compelling experimental evidence showing that magnetic recording can be applied for imprinting in a soft magnetic layer the flux trajectory taking place in a superconducting layer at cryogenic temperatures. This approach enables the ex situ observation at room temperature of the imprinted magnetic flux landscape obtained below the critical temperature of the superconducting state. The undeniable appeal of the proposed technique lies in its simplicity and the potential to improve the spatial resolution, possibly down to the scale of a few vortices.

show abstract

Quantitative magneto-optical investigation of superconductor/ferromagnet hybrid structures

Cited by 28 publications

References 70 publications

Statistics of thermomagnetic breakdown in Nb superconducting films

Statistics of thermomagnetic breakdown in Nb superconducting films

Upper critical fields in Ba2Ti2Fe2As4O single crystals: Evidence for dominant Pauli paramagnetic effect

Magnetic Recording of Superconducting States

Contact Info

Product

Resources

About