Kink State in a Stack of Intrinsic Josephson Junctions in Layered High-$T_c$ Superconductors and Terahertz Radiation

TL;DR

This paper discovers a new dynamic state in layered high-$T_c$ superconductors' intrinsic Josephson junctions, featuring phase kinks that enable strong terahertz radiation, aligning with recent experimental findings.

Contribution

It introduces a novel kink state in stacked Josephson junctions that facilitates efficient terahertz emission without external magnetic fields.

Findings

Identifies a new dynamic kink state in Josephson junction stacks.

Shows the state supports strong terahertz radiation.

Demonstrates compatibility with recent experiments.

Abstract

A new family of dynamic states are found in a stack of inductively coupled intrinsic Josephson junctions in the absence of an external magnetic field. In this state, $(2m_l+1)\pi$ phase kinks with integers $m_l$'s stack along the c axis and lock neighboring junction together. Large dc power is pumped into plasma oscillation via kinks at the cavity resonance. The plasma oscillation is uniform along the c axis with the frequency satisfying the ac Josephson relation. Thus this state supports strong terahertz radiation and seems to be compatible with the recent experimental observations.