Vortex matching at 6 T in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:msub><mml:mi>YBa</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Cu</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mn>7</mml:mn><mml:mo>−</mml:mo><mml:mi>δ</mml:mi></mml:mrow></mml:msub></mml:math> thin films by imprinting a 20-nm periodic pinning array with a focused helium-ion beam
Max Karrer, Bernd Aichner, Katja Wurster, César Magén, Christoph Schmid, Robin Hutt, Barbora Budinská, Oleksandr V. Dobrovolskiy, R. Kleiner, W. Lang, E. Goldobin, D. Koelle
Abstract
Controlled engineering of vortex pinning sites in copper-oxide superconductors is a critical issue in manufacturing devices based on magnetic flux quanta. To address this, we employed a focused <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><a:mi>He</a:mi></a:math>-ion beam (<d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><d:mi>He</d:mi></d:math>-FIB) to irradiate thin <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><g:msub><g:mi>YBa</g:mi><g:mn>2</g:mn></g:msub><g:msub><g:mi>Cu</g:mi><g:mn>3</g:mn></g:msub><g:msub><g:mrow><g:mi mathvariant="normal">O</g:mi></g:mrow><g:mrow><g:mn>7</g:mn><g:mo>−</g:mo><g:mi>δ</g:mi></g:mrow></g:msub></g:math> films and create ultradense hexagonal arrays of defects with lattice spacings as small as 20 nm. Critical current and magnetoresistance measurements demonstrate efficient pinning by a matching field of 6 T visible in a huge temperature range from the critical temperature <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><k:msub><k:mi>T</k:mi><k:mi>c</k:mi></k:msub></k:math> down to 2 K. These results show that <n:math xmlns:n="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><n:mi>He</n:mi></n:math>-FIB irradiation provides excellent opportunities for the development and application of superconducting fluxonic devices based on Abrikosov vortices. In particular, our findings suggest that such devices can operate at temperatures far below <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><q:msub><q:mi>T</q:mi><q:mi>c</q:mi></q:msub></q:math>, where superconductivity is robust. Published by the American Physical Society 2024