Sketched Nanoscale <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow><mml:mi>KTaO</mml:mi></mml:mrow><mml:mn>3</mml:mn></mml:msub></mml:math>-Based Superconducting Quantum Interference Device

The discovery of two-dimensional superconductivity in <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:msub><a:mrow><a:mi>LaAlO</a:mi></a:mrow><a:mn>3</a:mn></a:msub><a:mo stretchy="false">/</a:mo><a:msub><a:mrow><a:mi>KTaO</a:mi></a:mrow><a:mn>3</a:mn></a:msub></a:mrow></a:math> (111) and (110) interfaces has raised significant interest in this system. In this paper, we report the first successful fabrication of a direct current superconducting quantum interference device (dc-SQUID) in the KTO system. The key device elements, superconducting weak links, are created by conductive atomic force microscope lithography, which can reversibly control the conductivity at the LAO/KTO (110) interface with nanoscale resolution. The periodic modulation of the SQUID critical current <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"><d:mrow><d:msub><d:mi>I</d:mi><d:mi mathvariant="normal">c</d:mi></d:msub><d:mo stretchy="false">(</d:mo><d:mi>B</d:mi><d:mo stretchy="false">)</d:mo></d:mrow></d:math> with magnetic field corresponds well with our theoretical modeling, which reveals a large kinetic inductance of the superconducting two-dimensional electron gas in KTO. The kinetic inductance of the SQUID is tunable by electrical gating from the back, due to the large dielectric constant of KTO. The demonstration of weak links and SQUIDs in KTO broadens the scope for exploring the underlying physics of KTO superconductivity, including the role of spin-orbit coupling, pairing symmetry, and inhomogeneity. It also promotes KTO as a versatile platform for a growing family of quantum devices, which could be applicable in the realm of quantum computing and information.