Microwave distribution in stacked Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+x}$ intrinsic Josephson junctions in a transmission-line geometry

TL;DR

This study investigates microwave distribution in a microfabricated stack of intrinsic Josephson junctions made of Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+x}$, revealing insights crucial for high-frequency device applications like THz oscillators.

Contribution

It introduces a method to analyze microwave transmission modes inside IJJs stacks using critical current suppression measurements at W band frequencies.

Findings

Microwave distribution affects critical current suppression.

Transmission-line geometry influences microwave modes.

Insights support development of THz oscillators.

Abstract

The microwave distribution inside a rectangular stack (15 $\mu$m$\times$0.72 $\mu$m$\times$60 nm) of Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+x}$ intrinsic Josephson junctions (IJJs) was studied. The stack was microfabricated into a transmission-line geometry, with a few hundred nm thick Au layers deposited on top and bottom of the stack. The microwave distribution was monitored by measuring the anomalous suppression of the tunneling critical current of the IJJs with varied microwave power at frequencies in the W band. This technique can provide valuable information on the microwave transmission modes inside the sandwiched stack of IJJs, which is utterly important for the high-frequency device applications using IJJs, such as fluxon-flow THz oscillators.