Theory of phase dynamics in intrinsic Josephson junctions with multigap superconducting layers

Ota, Yukihiro; Machida, Masahiko  ; Koyama, Tomio*

We construct a theory of dynamical behavior in intrinsic Josephson junction stacks (IJJ's) with multi-gap superconducting layers, motivated by recent discovery rush of highly-anisotropic iron-based superconductors with a thick perovskite block layers. The theory predicts the existence of two kinds of phase modes, one of which is the Josephson plasma mode and other of which is the Leggett's mode. The IJJ's with multiple tunneling channels have a novel energy scale, inter-band Josephson coupling on each superconducting layer which generates a mass of the Leggett's mode. We discuss a cooperative phenomena induced by such a coupling in addition to capacitive and inductive couplings between the superconducting layers.