Spatial Resolution Assessment of Nano-SQUIDs Made by Focused Ion Beam

Abstract

The ability to reduce SQUID dimensions into the submicrometer or nanometer regime points the way towards novel applications, particularly in emerging fields such as quantum information processing, single-photon/particle detection, and experimental studies of nano-scale entities such as Bose-Einstein condensates. We report here on our ongoing work combining traditional thin-film and photolithographic fabrication processes with computer-aided-design software and focused ion beam milling to realize sub-micrometer superconducting structures. Their magnetic field sensitivity, noise behavior, spatial resolution, and prospects for magnetic spin detection are discussed.

Performance of nano superconducting quantum interference devices for small spin cluster detection

“…19 For a circular loop, such increasing can be approximately evaluated as A eff = A g ͕͓1+⌳͑T͒ / a͔͖ 2 , where ⌳͑T͒ = 2 ͑T͒ / d is the two-dimensional Pearl screening length, ͑T͒ is the London penetration depth at the temperature T, d is the superconducting film thickness, and A g is the geometrical area of the SQUID loop. With typical values of loop radius and film thickness employed in nano-SQUID fabrication, the correction factor, in general, cannot be neglected.…”

Performance of nano superconducting quantum interference devices for small spin cluster detection

“…19 For a circular loop, such increasing can be approximately evaluated as A eff = A g ͕͓1+⌳͑T͒ / a͔͖ 2 , where ⌳͑T͒ = 2 ͑T͒ / d is the two-dimensional Pearl screening length, ͑T͒ is the London penetration depth at the temperature T, d is the superconducting film thickness, and A g is the geometrical area of the SQUID loop. With typical values of loop radius and film thickness employed in nano-SQUID fabrication, the correction factor, in general, cannot be neglected.…”

Contribution of Processes in SN Electrodes to the Transport Properties of SN-N-NS Josephson Junctions

“…The approach we have demonstrated in this paper allows calculation of the parameters of the equivalent scheme of SN-N-NS, BVT, and DB structures. Their representation in the form of a serial connection of the Josephson contact having and the linear inductance of conductive electrodes is useful for the interpretation of experimental data in bridges [ 13 , 86 ], analysis of processes in nano-SQUIDs [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ], experimental determination of inductance in various low-current superconducting devices [ 3 , 9 ], and in the design of digital circuits [ 12 , 13 , 14 ].…”

Nano Superconducting Quantum Interference device: A powerful tool for nanoscale investigations

“…Moreover, the filamentary model does not consider flux focusing due to finite width of the superconducting tracks [110,145]. For a circular loop, such increasing can be approximately evaluated as A eff =Α g [(1+Λ(T)/a)] 2 where Λ(T)=λ 2 (T)/d is the two-dimensional effective penetration depths [146], λ(T) is the London penetration depth at the temperature T, d is the superconducting film thickness and A g is the geometrical area of the SQUID loop. With typical values of loop radius and film thickness employed in nano-SQUID fabrication, the correction factor may not be negligible.…”

Performance of nano superconducting quantum interference devices for small spin cluster detection

“…19 For a circular loop, such increasing can be approximately evaluated as A eff = A g ͕͓1+⌳͑T͒ / a͔͖ 2 , where ⌳͑T͒ = 2 ͑T͒ / d is the two-dimensional Pearl screening length, ͑T͒ is the London penetration depth at the temperature T, d is the superconducting film thickness, and A g is the geometrical area of the SQUID loop. With typical values of loop radius and film thickness employed in nano-SQUID fabrication, the correction factor, in general, cannot be neglected.…”

Contribution of Processes in SN Electrodes to the Transport Properties of SN-N-NS Josephson Junctions

“…The approach we have demonstrated in this paper allows calculation of the parameters of the equivalent scheme of SN-N-NS, BVT, and DB structures. Their representation in the form of a serial connection of the Josephson contact having and the linear inductance of conductive electrodes is useful for the interpretation of experimental data in bridges [ 13 , 86 ], analysis of processes in nano-SQUIDs [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ], experimental determination of inductance in various low-current superconducting devices [ 3 , 9 ], and in the design of digital circuits [ 12 , 13 , 14 ].…”

Nano Superconducting Quantum Interference device: A powerful tool for nanoscale investigations

“…Moreover, the filamentary model does not consider flux focusing due to finite width of the superconducting tracks [110,145]. For a circular loop, such increasing can be approximately evaluated as A eff =Α g [(1+Λ(T)/a)] 2 where Λ(T)=λ 2 (T)/d is the two-dimensional effective penetration depths [146], λ(T) is the London penetration depth at the temperature T, d is the superconducting film thickness and A g is the geometrical area of the SQUID loop. With typical values of loop radius and film thickness employed in nano-SQUID fabrication, the correction factor may not be negligible.…”

Performance of nano superconducting quantum interference devices for small spin cluster detection

“…19 For a circular loop, such increasing can be approximately evaluated as A eff = A g ͕͓1+⌳͑T͒ / a͔͖ 2 , where ⌳͑T͒ = 2 ͑T͒ / d is the two-dimensional Pearl screening length, ͑T͒ is the London penetration depth at the temperature T, d is the superconducting film thickness, and A g is the geometrical area of the SQUID loop. With typical values of loop radius and film thickness employed in nano-SQUID fabrication, the correction factor, in general, cannot be neglected.…”

Contribution of Processes in SN Electrodes to the Transport Properties of SN-N-NS Josephson Junctions

“…The approach we have demonstrated in this paper allows calculation of the parameters of the equivalent scheme of SN-N-NS, BVT, and DB structures. Their representation in the form of a serial connection of the Josephson contact having and the linear inductance of conductive electrodes is useful for the interpretation of experimental data in bridges [ 13 , 86 ], analysis of processes in nano-SQUIDs [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ], experimental determination of inductance in various low-current superconducting devices [ 3 , 9 ], and in the design of digital circuits [ 12 , 13 , 14 ].…”

Nano Superconducting Quantum Interference device: A powerful tool for nanoscale investigations

“…Moreover, the filamentary model does not consider flux focusing due to finite width of the superconducting tracks [110,145]. For a circular loop, such increasing can be approximately evaluated as A eff =Α g [(1+Λ(T)/a)] 2 where Λ(T)=λ 2 (T)/d is the two-dimensional effective penetration depths [146], λ(T) is the London penetration depth at the temperature T, d is the superconducting film thickness and A g is the geometrical area of the SQUID loop. With typical values of loop radius and film thickness employed in nano-SQUID fabrication, the correction factor may not be negligible.…”