Fabrication of submicron La$_{2-x}$Sr$_{x}$CuO$_{4}$ intrinsic Josephson junction stacks

TL;DR

This paper reports the successful fabrication of submicron La$_{2-x}$Sr$_{x}$CuO$_{4}$ intrinsic Josephson junction stacks using a novel combination of focused ion beam and argon ion etching, enabling precise control of junction number.

Contribution

Introduces a new fabrication method for LSCO IJJ stacks that allows for potentially single-junction control, advancing high-temperature superconducting qubit technology.

Findings

Resistive multi-branches observed in fabricated stacks

Achieved submicron LSCO IJJ stacks from single crystals

Potential for precise control of IJJ number

Abstract

Intrinsic Josephson junction (IJJ) stacks of cuprate superconductors have potential to be implemented as intrinsic phase qubits working at relatively high temperatures. We report success in fabricating submicron La$_{2-x}$Sr$_{x}$CuO$_{4}$ (LSCO) IJJ stacks carved out of single crystals. We also show a new fabrication method in which argon ion etching is performed after focused ion beam etching. As a result, we obtained an LSCO IJJ stack in which resistive multi-branches appeared. It may be possible to control the number of stacked IJJs with an accuracy of a single IJJ by developing this method.