Pair suppression caused by mosaic-twist defects in superconducting Sr2RuO4 thin-films prepared using pulsed laser deposition

Abstract

Sr 2 RuO 4 (SRO 214) 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 SRO 214 remains controversial. Solving this problem is massively impeded by the fact that superconducting SRO 214 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 SRO 214 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 Sr 3 Ru 2 O 7 (SRO 327). By systematically varying the SRO 214 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.

Quantum Oscillations and the Quasiparticle Properties of Thin Film Sr$_2$RuO$_4$

“…The difficulty stems from the extreme sensitivity of Sr 2 RuO 4 to even minute levels of disorder-single crystals with greater than 1 µOhm-cm residual resistivity do not superconduct [9]. With the advent of Sr 2 RuO 4 films that are clean enough to show superconductivity on many different substrates [10][11][12], it is worth investigating whether the superconductivity is a product of film quality, substrate strain, or both, how the quasiparticle properties are modified by the substrate, and what types of defects might be limiting the quasiparticle mean free path.…”

Inverse Proximity Effects at Spin-Triplet Superconductor-Ferromagnet Interface

“…This magnetic scenario supports the general investigation of the inverse proximity effects in the presence of different types of magnetic leakage into the TSC. The recent de- velopments in the fabrication of Sr 2 RuO 4 thin films [60][61][62][63] and hetero-structures allow to experimentally investigate the properties of the inverse proximity effect, which we discuss in our work. This can provide relevant experimental paths to address the debate about the nature of the superconductivity in Sr 2 RuO 4 .…”