Observation of Superconducting Device Using Magnetic Imaging System with a Micro-DC Superconducting Quantum Interference Device Magnetometer

Morooka, T.; Nakayama, Satoshi; Odawara, Akikazu; Chinone, Kazuo

doi:10.1143/jjap.38.l119

Cited by 32 publications

(11 citation statements)

References 7 publications

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“…The scanning SQUID microscope used here was quite similar to that reported in ref. 20. The d.c. SQUID was made of low-temperature Nb/AlO x /Nb tunnel junctions, and the radius of the pickup coil was 5 mm.…”

mentioning

confidence: 99%

Diamagnetic activity above Tc as a precursor to superconductivity in La2-xSrxCuO4 thin films

Iguchi

Yamaguchi

Sugimoto

2001

Nature

136

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Superconductors show zero resistance to electric current, and expel magnetic flux (the Meissner effect) below the transition temperature (Tc). In conventional superconductors, the 'Cooper pairs' of electrons that are responsible for superconductivity form only below Tc. In the unconventional high-Tc superconductors, however, a strong electron correlation is essential for pair formation: there is evidence that some pairs are formed above Tc in samples that have less than the optimal density of charge carriers (underdoped) and an energy gap-the 'pseudogap'-appears to be present. Moreover, excitations that look like the vortices that carry magnetic flux inside the superconducting state have been reported above Tc (refs 6, 7). Although the origin of the pseudogap remains controversial, phase fluctuations above Tc, leading to some form of local superconductivity or local pairing, seem essential. Here we report magnetic imaging (scanning SQUID microscopy) of La2-xSrxCuO4 thin films. Clear quantized vortex patterns are visible below Tc (18-19 K), and we observe inhomogeneous magnetic domains that persist up to 80 K. We interpret the data as suggesting the existence of diamagnetic regions that are precursors to the Meissner state.

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mentioning

confidence: 99%

Diamagnetic activity above Tc as a precursor to superconductivity in La2-xSrxCuO4 thin films

Iguchi

Yamaguchi

Sugimoto

2001

Nature

136

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“…However, the temperature of the observations was fixed at = T 3.0 K. A Cu wire coil was wound around the sample holder to generate a magnetic field. The details of this system are described elsewhere [23,24]. J eff is about ten times larger than the widely recognized Josephson penetration depth of ∼10 μm.…”

Section: Methodsmentioning

confidence: 99%

Observation of local magnetic distribution in ramp-edge Josephson junctions

Sugimoto

Iguchi

2017

J. Phys. Commun.

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The observation of magnetic images for ramp-edge Josephson junctions (JJ) by scanning SQUID microscopy is reported. The dependence of the trapped vortex at a JJ on the external magnetic field was investigated, and it was found to be consistent with the modulation of the maximum Josephson current, showing that the vortex was not continuously changing, but that the change was quantized. A novel vortex trapped at the junction under a relatively large field is observable, which increases in quantized units as the external field is increased. Three different types of ramp-edge junctions were also investigated, showing that the difference in the magnetic penetration around the junctions reflects the junction property. These results provide us easy and useful information and an evaluation method of the junctions and the superconductivity of the films with no lead line.

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“…6. The SQUID loop was originally designed for the effective diameter of 10 mm of the pick-up coil, the sensitivity is somewhat decreased by reducing the size of the pick-up coil down to 2 mm [60]. It turns out that this size is almost the smallest limit technically possible without modifying the rest of the SQUID system.…”

Section: Pick-up Sensing Coil and Designmentioning

confidence: 99%

Vortex states in high-T_c superconductors and superconductivity in modern nano-science and engineering

Kadowaki

2005

Science and Technology of Advanced Materials

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A brief review is given on the recent development of the vortex engineering research in our group with special emphasis on the geometrical confinement of vortices into micron-size of samples. We show that the static as well as dynamical nature of vortices is strongly affected by the geometrical constraints, which can be manipulated by the recent nano-technology engineering artificially. One of the spectacular phenomena in this context is a formation of self-organized vortex structures occuring both in static and dynamic manners. The static behaviors have been studied by the scanning SQUID microscope technique and the dynamical behaviors are mostly done in transport measurements. Some technical development of these methods is also discussed. We stress that a common generic concept here is the confinement in nano-scale superconducting systems by the existing surfaces (boundaries), which plays an essential role for the phenomena. Some typical examples are shown, such as results on the vortex arrangement in micron size superconducting disks, a formation of the giant vortex state in such a particular case and the dynamical effects of vortices, especially in the case of Josephson vortices confined in an intrinsic Josephson junction in micron size single crystal Bi 2 Sr 2 CaCu 2 O 8Cd , where the dynamical effect of the confinement provides rich linear and non-linear phenomena due to the excitation of Josephson plasma. Making use of Josephson plasma excitations, a generator operating at T (Hz) frequencies is proposed in this intrinsic Josephson junctions. These phenomena are expected to be all beneficial to potential applications. q

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Observation of Superconducting Device Using Magnetic Imaging System with a Micro-DC Superconducting Quantum Interference Device Magnetometer

Cited by 32 publications

References 7 publications

Diamagnetic activity above Tc as a precursor to superconductivity in La2-xSrxCuO4 thin films

Diamagnetic activity above Tc as a precursor to superconductivity in La2-xSrxCuO4 thin films

Observation of local magnetic distribution in ramp-edge Josephson junctions

Vortex states in high-T_c superconductors and superconductivity in modern nano-science and engineering

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Observation of Superconducting Device Using Magnetic Imaging System with a Micro-DC Superconducting Quantum Interference Device Magnetometer

Cited by 32 publications

References 7 publications

Diamagnetic activity above Tc as a precursor to superconductivity in La2-xSrxCuO4 thin films

Diamagnetic activity above Tc as a precursor to superconductivity in La2-xSrxCuO4 thin films

Observation of local magnetic distribution in ramp-edge Josephson junctions

Vortex states in high-Tc superconductors and superconductivity in modern nano-science and engineering

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Product

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Vortex states in high-T_c superconductors and superconductivity in modern nano-science and engineering