Anisotropic superconductivity at KTaO<sub>3</sub>(111) interfaces.

Arnault, Ethan G; Al-Tawhid, Athby H; Salmani-Rezaie, Salva; Muller, David A; Kumah, Divine P; Bahramy, Mohammad S; Finkelstein, Gleb; Ahadi, Kaveh · Sci Adv · 2023

basic_science · Level V

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Abstract

A two-dimensional, anisotropic superconductivity was recently found at the KTaO<sub>3</sub>(111) interfaces. The nature of the anisotropic superconducting transition remains a subject of debate. To investigate the origins of the observed behavior, we grew epitaxial KTaO<sub>3</sub>(111)-based heterostructures. We show that the superconductivity is robust against the in-plane magnetic field and violates the Pauli limit. We also show that the Cooper pairs are more resilient when the bias is along [11[Formula: see text]] (I ∥ [11[Formula: see text]]) and the magnetic field is along [1[Formula: see text]0] (<i>B</i> ∥ [1[Formula: see text]0]). We discuss the anisotropic nature of superconductivity in the context of electronic structure, orbital character, and spin texture at the KTaO<sub>3</sub>(111) interfaces. The results point to future opportunities to enhance superconducting transition temperatures and critical fields in crystalline, two-dimensional superconductors with strong spin-orbit coupling.