Using spin-polarized neutron reflectivity to probe mesoscopic vortex states in a Pb thin-film superconductor

Drew, Alan J.; Wisemayer, M. W.; Heron, D. O. G.; Lister, S. J. S.; Potenza, A.; Marrows, C. H.; Dalgliesh, Robert M.; Charlton, Timothy; Langridge, S.

doi:10.1103/physrevb.80.134510

Cited by 10 publications

(5 citation statements)

References 30 publications

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“…[10] for Nb(50nm) film using microwave surface impedance and with  = 110 nm obtained by PNR on Nb(600nm) sample [11]. The absence of vortices in the S film at high magnetic field in our case is explained by small thickness comparing to the vortex size [12,13].…”

Section: Nbmentioning

confidence: 58%

Structural, Magnetic, and Superconducting Characterization of the CuNi/Nb Bilayers of the S/F Type Using Polarized Neutron Reflectometry and Complementary Techniques

Khaydukov

Morari

Mustafa

et al. 2014

J Supercond Nov Magn

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Structural, magnetic, and superconducting properties of S/F bilayers Nb/Cu 40 Ni 60 deposited on silicon substrate have been characterized using polarized neutron reflectometry and complementary techniques. The study allowed to determine real thicknesses of the S and F layers as well as the r.m.s. roughness of the S/F interfaces. The latter does not exceed 1 nm, showing the high quality of the S/F interface. Using SQUID and a mutual inductance setup, we determined the superconducting transition temperatures of the samples, which are in agreement with the literature data. Using of polarized neutron reflectometry (PNR) for the single S layer allowed to determine the screening length λ of the superconducting layer, λ = 120 nm. This value is higher than the London penetration depth for pure niobium which may indicate that the superconductor is in the dirty

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Section: Nbmentioning

confidence: 58%

Structural, Magnetic, and Superconducting Characterization of the CuNi/Nb Bilayers of the S/F Type Using Polarized Neutron Reflectometry and Complementary Techniques

Khaydukov

Morari

Mustafa

et al. 2014

J Supercond Nov Magn

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“…As expected, the wider the stripe the shallower the confining potential and therefore the smaller H ‫ء‬ . 11 Interestingly, further increasing the field, first an almost square array of vortices is observed 12 before a more disordered configuration is achieved. The field H p at which the first vortex penetrates in narrow stripes and the formation of different vortex patterns have been previously investigated both theoretically [12][13][14][15][16][17][18][19][20] and experimentally.…”

mentioning

confidence: 99%

Direct visualization of the Campbell regime in superconducting stripes

et al. 2010

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A combination of scanning Hall microscopy and scanning ac-susceptibility measurements in superconducting stripes ͑ribbons͒ of width w Ͻ 10 m was used to observe the dimensional phase transitions of the vortex lattice and its stability under alternating fields. At low dc magnetic fields applied perpendicularly to the plane of the stripes, vortices form a one-dimensional chain at the center of the stripes. Above a certain field H ‫ء‬ ͑w͒, the vortex chain splits in two parallel rows displaced laterally in such a way that a zigzag vortex pattern is observed. By shaking the vortices with an external magnetic ac field and detecting their in-phase motion locally, we can identify the degree of mobility of each individual vortex. This technique allows us ͑i͒ to directly visualize the transition from intravalley ͑Campbell regime͒ to intervalley vortex motion as the amplitude of the ac modulation is increased and ͑ii͒ to accurately determine the temperature at which the vortex lattice freezes in a field-cooling experiment. The hallmark of type II superconductivity is the presence of quantized magnetic flux encircled by a rotating condensate of paired electrons when a sufficiently strong magnetic field is applied. The free motion of these fluxons leads to dissipation thus destroying the perfect conductivity of the system. The ever growing electricity demand has motivated for several decades a fierce strive for understanding, improving, and optimizing the mechanisms to prevent the fluxon's motion by introducing a rich diversity of pinning centers. 1Among the most powerful experimental methods used to determine the efficiency of pinning sites is the ac-susceptibility technique which consist of shaking the flux-line lattice with a small alternating magnetic field while recording its in-phase magnetic response.2 Pioneering theoretical works by Campbell and co-workers substantially contributed to comprehend and interpret the ac response of a superconducting system. 3,4 In the most simple version, two different regimes with distinctive ac responses can be identified. For a gentle ac shacking, flux lines oscillate inside the pinning potential following a reversible and low dissipative motion ͑Campbell regime͒. By increasing the strength of the ac excitation, the intravalley vortex motion first senses the anharmonicities of the potential well and eventually switches to an intervalley motion where vortices can hop from one pinning site to another. 5So far, all the experimental and theoretical reports are focused on global ac-susceptibility investigations where the recorded signal represents an average over millions of flux lines each of which trapped in a different pinning potential and subjected to a different environment. [6][7][8] In this paper, we introduce a local vortex imaging technique with singlevortex resolution which allows us to directly visualize the oscillatory motion of individual vortices submitted to harmonic ac excitations. The system to investigate consists of superconducting ribbons which, due to the proximity o...

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“…The key variable in our theoretical model is the vortex core fraction f n which can be approximated by f n = B/B c2 (T ) [2]. As shown by Drew [19], the time dependent Ginzburg Landau theory predicts the upper critical field in the thin film limit in parallel field as…”

Section: Discussionmentioning

confidence: 96%

Anisotropic behaviour of transmission through thin superconducting NbN film in parallel magnetic field

Šindler

Tesař

Koláček

et al. 2017

Physica C: Superconductivity and its Applications

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Using spin-polarized neutron reflectivity to probe mesoscopic vortex states in a Pb thin-film superconductor

Cited by 10 publications

References 30 publications

Structural, Magnetic, and Superconducting Characterization of the CuNi/Nb Bilayers of the S/F Type Using Polarized Neutron Reflectometry and Complementary Techniques

Structural, Magnetic, and Superconducting Characterization of the CuNi/Nb Bilayers of the S/F Type Using Polarized Neutron Reflectometry and Complementary Techniques

Direct visualization of the Campbell regime in superconducting stripes

Anisotropic behaviour of transmission through thin superconducting NbN film in parallel magnetic field

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