Effect of disorder on superconductivity and Rashba spin-orbit coupling in LaAlO3/SrTiO3 interfaces

by G. Singh, A. Jouan, S. Hurand, C. Feuillet-Palma, P. Kumar, A. Dogra,
R. Budhani, J. Lesueur and N. Bergeal

A rather unique feature of the two-dimensional electron gas formed at the interface between the two insulators LaAlO3 and SrTiO3 is to host both gate-tunable superconductivity and strong spin-orbit coupling. In the present work, we use the disorder generated by Cr substitution of Al atoms in LaAlO3 as a tool to explore the nature of superconductivity and spin-orbit coupling in these interfaces.We analyze the transport properties of three different samples whose only relevant difference is their elastic scattering time τe. A reduction of the superconducting Tc is observed with Cr doping consistent with an increase of electron-electron interaction in the presence of disorder. In addition, the evolution of spin-orbit coupling with gate voltage and Cr doping evidences a Dyakonov-Perel mechanism of spin relaxation (τSO ∝ 1/τe ) in the presence of a Rashba-type spin-orbit interaction.