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(a) Critical current density normalized to at , as a function of temperature for all films S1–S6. (b) Temperature dependence of which shows a gradual transition of to the Ginzburg-Landau-like temperature dependence (seen for films S5 and S6) with a decreasing . (c) Temperature dependence of resistivity for films S5 and S6. (d) Persistent current dissipation rate as a function of the normalized temperature for films S1 and S3–S5.
(a) Temperature dependence of for films S1, S3, and S4. Suppression of the persistent current is seen in films S1 and S3, both with larger than , below . If the persistent current is first generated in the film at and then cooled below , there is no change in the magnitude of the persistent circulation current, as indicated by the arrow. (b) Dependence of the persistent current self-field (field trapped at the ring’s center) measured for film S1 as a function of the applied external magnetic field. The saturation value of the trapped field is proportional to the magnitude of the critical current density. The trapped field is unstable at 9.3 and , but not at temperatures above .
Parameters that describe films S1–S6. is the transition temperature, determined as the temperature at which the supercurrent disappears (see Ref. 11), is the critical current density at , and is the thickness. Reduced of sample S3 is caused by aging in air at room temperature for two years.12 is the pulsed laser deposition followed by postannealing in a magnesium vapor. rf-MAG is the rf magnetron sputter deposition method.
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