Abstract
Sr2RuO4 (SRO214) is a prototypical unconventional superconductor. However, since the discovery of its superconductivity a quarter of a century ago, the symmetry of the bulk and surface superconducting states in single crystal SRO214 remains controversial. Solving this problem is massively impeded by the fact that superconducting SRO214 is extremely challenging to achieve in thin-films as structural defects and impurities sensitively annihilate superconductivity. Here we report a protocol for the reliable growth of superconducting SRO214 thin-films by pulsed laser deposition and identify universal materials properties that are destructive to the superconducting state. We demonstrate that careful control of the starting material is essential in order to achieve superconductivity and use a single crystal target of Sr3Ru2O7 (SRO327). By systematically varying the SRO214 film thickness, we identify mosaic twist as the key in-plane defect that suppresses superconductivity. The results are central to the development of unconventional superconductivity.
Highlights
Sr2RuO4 (SRO214) is a prototypical unconventional superconductor
There is a lack of experimental consistency in the underlying superconducting symmetry of SRO214, unconventional pairing states are expected on the surface due to broken inversion symmetry, which raises the prospect of coupling different superconducting symmetries via proximity effects with swave or even d-wave superconductors
A single crystal target of SRO327 provides 33% Ru excess that compensates for Ru loss during the high-temperature growth of SRO214 which, in conjunction with fine-control of laser fluence[32], reduces the volume fraction of impurity phases present in the films
Summary
Since the discovery of its superconductivity a quarter of a century ago, the symmetry of the bulk and surface superconducting states in single crystal SRO214 remains controversial Solving this problem is massively impeded by the fact that superconducting SRO214 is extremely challenging to achieve in thin-films as structural defects and impurities sensitively annihilate superconductivity. This work was later reproduced by our group[29] in one sample albeit with an extremely broad (1.6 K) superconducting transition and an elevated Tc of 1.9 K This result indicated inhomogeneous superconductivity due to out-of-plane defects from stacking faults that create local strain, which locally enhances Tc. Recently, superconducting films of SRO214 have been grown by molecular beam epitaxy on LSAT with a Tc of 1.1 K using a Ru-rich flux during growth to reduce Ru loss[30]. The Tc was further enhanced to 1.9 K by depositing onto single terminated (1 1 0) NdGaO3 due to the associated misfit strain[31]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
