Scanning SQUID microscopy of sparsely twinned YBa2Cu3O7−δ

Kathryn A. Moler; John R. Kirtley; Ruixing Liang; Douglas Bonn; Walter N. Hardy

doi:10.1103/PhysRevB.55.12753

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Scanning SQUID microscopy of sparsely twinned YBa2Cu3O7−δ

Kathryn A. Moler, John R. Kirtley, Ruixing Liang, Douglas Bonn, Walter N. Hardy

DOI 10.1103/PhysRevB.55.12753 · Physical Review B

T1

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Abstract

Magnetic images of two sparsely twinned YBa2Cu3O7−δ single crystals were taken in low applied magnetic fields (Ha<100 mG) with a scanning SQUID microscope. The SQUID sensors have 4 or 8 μm pickup loops and a magnetic flux resolution of 10−3hc/2e under normal operating conditions. The images showed Meissner screening with a large demagnetization factor and isolated trapped vortices. The trapped vortices carried integral (hc/2e) magnetic flux and were much smaller than the spatial resolution of the sensor. At this level of resolution, there was no evidence for unusual magnetic features, such as fractional vortices, associated with the twin boundaries.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
YBa2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	93.1	Pressure not reported	unknown
YBa2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	60	Pressure not reported	unknown