Zusammenfassung
A scheme for measuring small intrinsic critical currents I c in nanoscale devices is described. Changes in Josephson inductance L J are converted to frequency variations that are recorded via microwave reflection measurements at 700-800 MHz. The critical current is determined from the frequency shift of the reflection magnitude at zero phase bias assuming a sinusoidal current-phase relation. The ...
Zusammenfassung
A scheme for measuring small intrinsic critical currents I c in nanoscale devices is described. Changes in Josephson inductance L J are converted to frequency variations that are recorded via microwave reflection measurements at 700-800 MHz. The critical current is determined from the frequency shift of the reflection magnitude at zero phase bias assuming a sinusoidal current-phase relation. The method is used to study a multiwalled carbon nanotube transistor with Pd/Nb contacts inside a resistive on-chip environment. We observe gate-tunable critical currents up to I c ~ 8Â nA corresponding to L J > 40Â nH. The method presented is also applicable to devices shunted by closed superconducting loops.
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