Properties of nanopatterned pins generated in a superconductor with FIB

Shaw, Gorky; Mandal, Paulami; Bag, Biplab; Banerjee, S. S.; Tamegai, T.; Suderow, Hermann

doi:10.1016/j.apsusc.2011.05.011

Cited by 6 publications

(6 citation statements)

References 15 publications

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“…While the patterned region appears to be strongly shielding at lower fields and largely devoid of vortices, there seems to be a significant increase in the local field B z (δB z ∼ 3 G) in response to a small change in H (δH = 1 Oe), allowing for a stronger concentration of enhanced flux inside the patterned region in response to δH, at higher fields. Some of our earlier observations [18] had shown dark contrast inside the patterned region, and consequent large B z gradient in the vicinity of the patterned region. The gradients in magnetic field are associated with shielding currents circulating around the patterned region.…”

Section: Magneto-optical Imagingmentioning

confidence: 68%

“…Bulk magnetization measurements on the sample nanopatterned with blind holes revealed a dynamic weak to strong pinning crossover. We also recently reported on the observation of highly non-uniform field gradients sustained in the vicinity of the patterned region in a single crystal of Bi 2 Sr 2 CaCu 2 O 8 studied with the local magneto-optical imaging technique [18].…”

Section: Introductionmentioning

confidence: 99%

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Generating strong magnetic flux shielding regions in a single crystal of Bi₂Sr₂CaCu₂O₈using a blind hole array

Shaw¹,

Bag²,

Banerjee³

et al. 2012

Supercond. Sci. Technol.

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Magneto-optical imaging studies in a single crystal of Bi2Sr2CaCu2O8 partially patterned with a hexagonal array of pinning centers (blind holes) reveal local features in the patterned region which are distinct compared to the pristine unpatterned regions in the sample. The patterned area exhibits a strongly diamagnetic local magnetization response and is characterized by a local penetration field enhanced by a factor of three. We show that strong shielding currents around the periphery of the nanopatterned region create a barrier which prevents vortex entry into the patterned region thus sustaining an effectively flux-free state up to the enhanced penetration field.

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Section: Magneto-optical Imagingmentioning

confidence: 68%

Section: Introductionmentioning

confidence: 99%

Generating strong magnetic flux shielding regions in a single crystal of Bi₂Sr₂CaCu₂O₈using a blind hole array

Shaw¹,

Bag²,

Banerjee³

et al. 2012

Supercond. Sci. Technol.

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“…Structured thin films have shown promise for applications in different areas, including electronics and medicine. In particular, micro- and nanoscopic patterned superconducting films have received attention as their electric and magnetic properties may be optimized for technological purposes [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. In this context, focused ion beam (FIB) milling is an extraordinary tool that allows to obtain structures not possible to design by other nanofabrication methods [ 14 , 15 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

“…In this context, focused ion beam (FIB) milling is an extraordinary tool that allows to obtain structures not possible to design by other nanofabrication methods [ 14 , 15 , 16 ]. FIB can reach spatial accuracy of about 20 nm and has been used to control the superconducting properties of several materials, including niobium films [ 4 , 6 , 8 , 10 , 13 , 17 , 18 , 19 , 20 ]. A serious drawback, however, is an inevitable contamination due to ion implantation that may cause severe damage to the milled material, modifying its physical characteristics [ 15 , 21 ] and being detrimental to superconducting specimens [ 22 , 23 ].…”

Section: Introductionmentioning

confidence: 99%

Superconducting Properties and Electron Scattering Mechanisms in a Nb Film with a Single Weak-Link Excavated by Focused Ion Beam

et al. 2021

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Granularity is one of the main features restricting the maximum current which a superconductor can carry without losses, persisting as an important research topic when applications are concerned. To directly observe its effects on a typical thin superconducting specimen, we have modeled the simplest possible granular system by fabricating a single artificial weak-link in the center of a high-quality Nb film using the focused ion beam technique. Then, its microstructural, magnetic, and electric properties in both normal and superconducting states were studied. AC susceptibility, DC magnetization, and magneto-transport measurements reveal well-known granularity signatures and how they negatively affect superconductivity. Moreover, we also investigate the normal state electron scattering mechanisms in the Boltzmann theory framework. The results clearly demonstrate the effect of the milling technique, giving rise to an additional quadratic-in-temperature contribution to the usual cubic-in-temperature sd band scattering for the Nb film. Finally, by analyzing samples with varying density of incorporated defects, the emergence of the additional contribution is correlated to a decrease in their critical temperature, in agreement with recent theoretical results.

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“…Thus j c is a measure of the vortex pinning strength. Recent strategies to artificially enhance pinning involve making the vortex lattice commensurate with an artificially generated lattice (ordered array) of pins [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The vortex lattice is said to be commensurate with an ordered array of pins when the inter-vortex spacing (a 0 ), µ a B 1 0 (where B is magnetic field) matches with the inter-pin spacing (d) (here we consider that each pin can accommodate only a single vortex).…”

Section: Introductionmentioning

confidence: 99%

Metastable inhomogeneous vortex configuration with non-uniform filling fraction inside a blind hole array patterned in a BSCCO single crystal and concentrating magnetic flux inside it

Shaw

Banerjee

Tamegai

et al. 2016

Supercond. Sci. Technol.

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Using magneto-optical imaging, we map the local magnetic field distribution inside a hexagonally ordered array of blind holes patterned in BSCCO single crystals. The nature of the spatial distribution of local magnetic field and shielding currents across the array reveals the presence of a non-uniform vortex configuration partially matched with the blind holes at sub-matching fields. We observe that the filling fraction is different in two different regions of the array. The mean vortex configuration within the array is described as a patchy vortex configuration with the patches having different mean filling fraction. The patchy nature of the vortex configuration is more pronounced at partial filling of the array at low fields while the configuration becomes more uniform with a unique filling fraction at higher fields. The metastable nature of this patchy vortex configuration is revealed by the application of magnetic field pulses of fixed height or individual pulses of varying height to the array. The metastability of the vortex configuration allows a relatively easy way of producing flux reorganization and flux focusing effects within the blind hole array. The effect of the magnetic field pulses modifies the vortex configuration within the array and produces a uniform enhancement in the shielding current around the patterned array edges. The enhanced shielding current concentrates magnetic flux within the array by driving vortices away from the edges and towards the center of the array. The enhanced shielding current also prevents the uninhibited entry of vortices into the array. We propose that the metastable patchy vortex configuration within the blind hole array is due to a non-uniform pinning landscape leading to non-uniform filling of individual blind holes.

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Properties of nanopatterned pins generated in a superconductor with FIB

Cited by 6 publications

References 15 publications

Generating strong magnetic flux shielding regions in a single crystal of Bi₂Sr₂CaCu₂O₈using a blind hole array

Generating strong magnetic flux shielding regions in a single crystal of Bi₂Sr₂CaCu₂O₈using a blind hole array

Superconducting Properties and Electron Scattering Mechanisms in a Nb Film with a Single Weak-Link Excavated by Focused Ion Beam

Metastable inhomogeneous vortex configuration with non-uniform filling fraction inside a blind hole array patterned in a BSCCO single crystal and concentrating magnetic flux inside it

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Properties of nanopatterned pins generated in a superconductor with FIB

Cited by 6 publications

References 15 publications

Generating strong magnetic flux shielding regions in a single crystal of Bi2Sr2CaCu2O8using a blind hole array

Generating strong magnetic flux shielding regions in a single crystal of Bi2Sr2CaCu2O8using a blind hole array

Superconducting Properties and Electron Scattering Mechanisms in a Nb Film with a Single Weak-Link Excavated by Focused Ion Beam

Metastable inhomogeneous vortex configuration with non-uniform filling fraction inside a blind hole array patterned in a BSCCO single crystal and concentrating magnetic flux inside it

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Generating strong magnetic flux shielding regions in a single crystal of Bi₂Sr₂CaCu₂O₈using a blind hole array

Generating strong magnetic flux shielding regions in a single crystal of Bi₂Sr₂CaCu₂O₈using a blind hole array