Enhanced localized superconductivity in Sr₂RuO₄thin film by pulsed laser deposition

Abstract

Superconducting c-axis-oriented Sr2RuO4 thin film has been fabricated using pulsed laser deposition. Although the superconductivity is localized, the onset critical temperature is enhanced over the bulk value. X-ray microstructural analysis of Sr2RuO4 superconducting and non-superconducting thin films suggests the existence of the localized stacking faults and an overall c-axis lattice expansion which may account for the locally enhanced superconductivity.

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

“…The first successful report of a superconducting thin-film of SRO 214 nearly a decade ago was fabricated by pulsed laser deposition from a stoichiometric (polycrystalline) target of SRO 214 on (0 0 1) (La 0.3 Sr 0.7 )(Al 0.65 Ta 0.35 )O 3 (LSAT) single crystals, and required high-temperature layer-by-layer growth 28 . 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 T c 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 T c . Recently, superconducting films of SRO 214 have been grown by molecular beam epitaxy on LSAT with a T c of 1.1 K using a Ru-rich flux during growth to reduce Ru loss 30 .…”

Electronic and optical properties of La-doped Sr3Ir2O7 epitaxial thin films

“…The formation of these defects causes translation boundary defects in the compound which result in an out-of-plane shift between regions compared with the ideal crystal structure. Although these extra layered intergrowths are not frequently observed in single crystals, they are common in epitaxial thin-films due to the thermodynamic non-equilibrium process of synthesis [49][50][51].…”

“…Note that such structural defects strongly affect materials properties in general. For example, stacking faults can alter or even eliminate 9 superconductivity in YBa2Cu3O7-δ and Sr2RuO4 [48,[51][52][53][54]. Attempts to synthesize superconducting Sr2RuO4 thin-films have had mixed results [53,[55][56][57][58].…”

Electronic and vibrational signatures of ruthenium vacancies in Sr2RuO4 thin films

“…Despite the fundamental interest and potential applications, the growth of high quality ruthenate thin films has proven to be very challenging due to the nature of ruthenium and its oxides 10,[14][15][16][17][18][19] . In fact, the high volatility of ruthenium oxides (RuO x=2,3,4 ) leads to ruthenium deficiency, as shown in numerous reports 14,15,[20][21][22][23] .…”

“…The ruthenium deficiency increases the resistivity and reduces the Curie temperature of SrRuO 3 and is detrimental to superconductivity in Sr 2 RuO 4 . In extreme cases, SrRuO 3 and Sr 2 RuO 4 even show semiconducting behavior at low temperatures 17,21 . Superconductivity in Sr 2 RuO 4 is extremely sensitive to defects, such as nonmagnetic impurities and lattice imperfections and thus it requires high quality samples 24,25 .…”