Superconducting Pinning by Magnetic Domains in a Ferromagnet-Superconductor Bilayer

Cieplak, Marek; Adamus, Z.; Kończykowski, M.; Chen, X. M.; Byczuk, A.; Abal’oshev, A.; Sang, H.; Chien, C. L.

doi:10.12693/aphyspola.106.693

Cited by 4 publications

(7 citation statements)

References 10 publications

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“…The deviation of s from 1 or 0 leads to a strong asymmetry of the loops with respect to the direction of H, indicating the enhancement of vortex pinning when H is positive. This is a result of the magnetic pinning induced by the presence of positive residual magnetic domains, similar to the one described previously in Nb5 sample [4][5][6]. The magnitude of the pinning enhancement is larger in Nb8 sample by a factor of about 1.5, which may be attributed to a larger magnetic moment resulting from the larger amount of Co/Pt repeats.…”

Section: Magnetic Pinningsupporting

confidence: 82%

“…The loop is typical of samples with perpendicular magnetic anisotropy, with rapid decrease in magnetic moment in the first stage of the MRP, followed by a slower decrease (tail) in the second stage when the remaining uninverted domains are gradually removed by increasing magnetic field. The loop for Nb5 sample is similar, as described previously [4][5][6], except for coercive fields which are 610 Oe and 700 Oe for the samples Nb5 and Nb8, respectively. The magnetic force microscope (MFM) imaging in the remnant state at 300 K shows that the MRP in Nb8 sample starts from several nucleation centers, from which a fractal structure of inverted domains gradually grows to cover the whole sample.…”

Section: Samplesmentioning

confidence: 89%

“…The interaction of the magnetic dipole and the vortex introduces the contribution to the energy of the dipole-vortex system, E = −mB, where m is the dipole moment, and B is magnetic field of a vortex [2]. It follows that the pinning is sensitive to the relative orientation between m and the external magnetic field H. The sensitivity of the pinning in the FSBs to the H direction has been demonstrated in several recent experiments [3][4][5][6]. The details of the behavior of the magnetic domain-induced pinning are not yet studied.…”

Section: Introductionmentioning

confidence: 93%

“…Depending on the amount of repeats of the Co/Pt superlattice, the MRP may proceed by domain wall motion, or by the nucleation of many inverted centers [7]. So far, we have studied the magnetic pinning induced by the first type of MRP, observed in the Co/Pt superlattice with small amount of repeats [4][5][6]. In the present study we compare it with the second type of the MRP.…”

Section: Introductionmentioning

confidence: 99%

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Vortex Pinning in Ferromagnet/Superconductor Bilayers - the Dependence on the Ferromagnetic Layer and Temperature

et al. 2006

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The behavior of vortex pinning induced by the magnetic domain reversal is studied in the ferromagnet/superconductor bilayers in which superconducting film is niobium and the ferromagnetic layers are the Co/Pt superlattices with perpendicular magnetic anisotropy. The local magnetic field across narrow ferromagnet/superconductor bilayer stripe is measured using a line of miniature Hall sensors. The pinning is studied for samples with different amount of repeats of Co/Pt superlattice, and as a function of temperature.

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Section: Magnetic Pinningsupporting

confidence: 82%

Section: Samplesmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

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Vortex Pinning in Ferromagnet/Superconductor Bilayers - the Dependence on the Ferromagnetic Layer and Temperature

et al. 2006

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“…The domain structure in FSB's may be reversibly defined and erased allowing easy modulation of pinning. While there are many experiments which confirm the existence of the MP, only few of them attempt to correlate the vortex dynamics in the FSB's with the geometry of the magnetic domain patterns [3][4][5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Vortex Dynamics in Ferromagnetic/Superconducting Bilayers

et al. 2008

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The dependence of vortex dynamics on the geometry of magnetic domain pattern is studied in the superconducting/ferromagnetic bilayers, in which niobium is a superconductor, and Co/Pt multilayer with perpendicular magnetic anisotropy serves as a ferrromagnetic layer. Magnetic domain patterns with different density of domains per surface area and different domain size, w, are obtained for Co/Pt with different thickness of Pt. The dense patterns of domains with the size comparable to the magnetic penetration depth (w ≥ λ) produce large vortex pinning and smooth vortex penetration, while less dense patterns with larger domains (w λ) enhance pinning less effectively and result in flux jumps during flux motion.

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The enhancement of vortex pinning in ferromagnet/superconductor bilayers

Cieplak

Adamus²,

Abal’oshev

et al. 2005

phys. stat. sol. (c)

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The magnetic-domain induced vortex pinning is studied in the ferromagnet/superconductor bilayers (FSB's), in which the F layers are Co/Pt multilayers with perpendicular magnetic anisotropy, and the S layers are either niobium or high temperature superconductor YBa 2 Cu 3 O 7 (YBCO). The magnetization measurements reveal the enhancement of the flux pinning in both types of FSB's during the reversal of the magnetization of the F layer, but the details of the behavior depend on the type of the S layer. In the case of niobium FSB the maximum of pinning appears when the F layer is in the final stage of the magnetic reversal process, while the FSB with YBCO shows the maximum when the F layer is saturated. The possible origins of these differences are discussed. IntroductionThe vortex pinning in superconductors determines the critical current density and therefore has a direct impact on the possible applications of superconducting materials. A large effort is directed towards the development of methods of the enhancement of flux pinning. Recently, a novel method, with the use of ferromagnet/superconductor bilayers (FSB), has been suggested [1]. It is based on the idea that the magnetic stripe domains in the F layer with a perpendicular magnetic anisotropy pin the vortex core in the S layer. The relative ease of the realignment of the stripe domains offers the possibility of the adjustment of vortex pinning using small magnetic fields, provided that the S and F layers are sufficiently separated by the buffer layer which eliminates the proximity effect. To date, several attempts have been made to study various FSB's, and the evidence has been accumulated that some pinning enhancement indeed occurs [2][3][4][5]. However, only one study, of the FSB's with lead S layers (weak type II superconductor in thin film form) addressed directly the question of the origins of the pinning enhancement, and found it related not to stripe domains, but to the isolated magnetic domains nucleated during the reversal of magnetization of the F layer [4].To shed more light on the behavior of the magnetic domain induced pinning, we compare here two classes of FSB's, containing either conventional type II superconductor, niobium, or the high temperature superconductor, YBCO. The intrinsic pinning is much stronger in YBCO, and one may expect that this has some impact on the behavior of FSB's. The preliminary results on the behavior of the niobium FSB's have been described elsewhere [6].

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Superconducting Pinning by Magnetic Domains in a Ferromagnet-Superconductor Bilayer

Cited by 4 publications

References 10 publications

Vortex Pinning in Ferromagnet/Superconductor Bilayers - the Dependence on the Ferromagnetic Layer and Temperature

Vortex Pinning in Ferromagnet/Superconductor Bilayers - the Dependence on the Ferromagnetic Layer and Temperature

Vortex Dynamics in Ferromagnetic/Superconducting Bilayers

The enhancement of vortex pinning in ferromagnet/superconductor bilayers

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