Macroscopic quantum tunneling in multigap superconducting Josephson junctions: Enhancement of escape rate via quantum fluctuations of the Josephson-Leggett mode

Yukihiro Ota; Masahiko Machida; Tomio Koyama

doi:10.1103/PhysRevB.83.060503

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Macroscopic quantum tunneling in multigap superconducting Josephson junctions: Enhancement of escape rate via quantum fluctuations of the Josephson-Leggett mode

Yukihiro Ota, Masahiko Machida, Tomio Koyama

DOI 10.1103/PhysRevB.83.060503 · Physical Review B

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Abstract

We theoretically study the macroscopic quantum tunneling (MQT) in a hetero Josephson junction formed by a conventional single-gap superconductor and a multigap superconductor such as iron-based superconductors and MgB2. In such a Josephson junction more than one phase difference is defined. We clarify their phase dynamics and construct a theory for the MQT in the multigap Josephson junctions. The dynamics of the phase differences are strongly affected by the Josephson-Leggett mode, which is the out-of-phase oscillation mode of the phase differences. The escape rate is calculated in terms of the effective action renormalized by the Josephson-Leggett mode at zero-temperature limit. We successfully predict drastic enhancement of the escape rate when the frequency of the Josephson-Leggett mode is less than the Josephson-plasma frequency.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
MgB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown