Magnetic bound states embedded in tantalum superconducting thin films

Abstract

In the fabrication of superconducting devices, both in situ and ex situ processes are utilized, making the removal of unwanted oxide layers and impurities under vacuum conditions crucial. Oxygen descumming and argon milling are standard in situ cleaning methods employed for device preparation. We investigated the impact of these techniques on tantalum superconducting thin films using scanning tunneling microscopy at millikelvin temperatures. We demonstrate that these cleaning methods inadvertently introduce magnetic bound states within the superconducting gap of tantalum, likely by oxygen impurities. These bound states can be detrimental to superconducting qubit devices, as they add to dephasing and energy relaxation.

References in corpus (5)

• Disentangling Losses in Tantalum Superconducting Circuits
• Magnetic anisotropy effects on quantum impurities in superconducting host
• Chemical profiles of the oxides on tantalum in state of the art superconducting circuits
• Zeeman effects on Yu-Shiba-Rusinov states
• Quantum spin driven Yu-Shiba-Rusinov multiplets and fermion-parity-preserving phase transition in K${}_3$C${}_{60}$

Cited by in corpus (1)

• Experimental Observation of Short-Range Magnetic Correlations in Amorphous Nb${}_2$O${}_5$ and Ta${}_2$O${}_5$ Thin Films