Numerical restoration of surface vortices in Nb films measured by a scanning SQUID microscope

Ito, Atsuki; Huy, Ho Thanh; Miyoshi, Hiroki; Hayashi, Masahiko; Ishida, Toshimasa

doi:10.1088/1742-6596/871/1/012021

Cited by 1 publication

(1 citation statement)

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“…In future, we need to investigate the reasons for the diagonal deviation of the peaks. We will consider the effect of the superconducting diamagnetism caused by the X, Y, and Z coils and their superconducting leads [19,32] by using the inverse Biot-Savart law to recover a true local magnetic field at the sample surface.…”

Section: Vortex Image Observed By Using An Xyz Coilmentioning

confidence: 99%

SQUID microscopy for mapping vector magnetic fields

Miyajima

Takeuchi

et al. 2019

Supercond. Sci. Technol.

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We mounted a vector-scanning superconducting quantum interference device (SQUID) sensor on a commercial SQUID microscope and successfully improved the sensitivity and spatial resolution of the sensor. Our proposed vector 3D SQUID sensor used multilayered niobium (Nb)-based technology; we realized three SQUID sensors in the structure of a vector pickup coil system on a single chip. The vector pickup coil system was built with three pickup coils that were orthogonal to one another to obtain the X, Y, and Z components of a magnetic field vector. To improve both sensitivity and spatial resolution, we attempted to reduce the inner diameter by increasing the number of windings of the pickup coils using the multilayered Nb process. The design value for the dc SQUID sensors was either the critical current density Jc = 320A cm−2 for two Josephson junctions (JJs) or the critical current Ic = 12.8μA for the 2μm × 2μm JJs. To measure the current–voltage (I–V) and voltage–flux (V–Φ) characteristics of a sensor, we constructed a homemade measurement system. The fundamental characteristics of our SQUID sensors were in good agreement with the design parameters. We mounted our vector SQUID sensor on a commercial scanning SQUID microscope (SQM2000, Seiko Instrument Inc.) with a single flux-locked loop channel to test one of the three channels. We repeated the measurements three times to obtain the X, Y, and Z componential images of the magnetic field from a single vortex, and we synthesized the 3D mapping of the magnetic field vectors from a single vortex. We proved that our sensor mounted on a SQUID microscope was suitable for measuring the X, Y, and Z components of a vector magnetic field.

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Section: Vortex Image Observed By Using An Xyz Coilmentioning

confidence: 99%