Intrinsic noise temperatures of YBa2Cu3O7-δ Josephson devices on bicrystal substrates and the upper frequency limit for their operation

J. Chen, H. Myoren, K. Nakajima, T. Yamashita, P. H. Wu

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6 Citations (Scopus)


Following a method proposed by Divin and Modovets [Sov. Tech. Phys. Lett. 9, 108 (1983)], we have measured at millimeter waveband the intrinsic noise temperatures TN of YBa2Cu3O7-δ Josephson junctions or dc superconducting quantum interference devices (SQUIDs) fabricated on SrTiO3, yttria-stabilized ZrO2, or Si bicrystal substrates. Over wide ranges of physical temperatures Tp and the junction's normal resistance RN, it was found that TN follows TP pretty well. This indicates that the intrinsic noise in the devices is dominated by Johnson noise. TN was also measured in cases where there is external magnetic field applied, or where there is another microwave radiation like the local oscillator in a mixer. The magnetic field or microwave radiation does not seem to affect TN in any appreciable way. To estimate the high frequency performance of the junctions on Si bicrystal substrates, direct irradiation by a far infrared laser at 1.81 THz is carried out and the clear first Shapiro step is observed.

Original languageEnglish
Pages (from-to)6536-6538
Number of pages3
JournalJournal of Applied Physics
Issue number11
Publication statusPublished - 1996 Dec 1

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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