Magnetic and Superconducting Ordering at LaAlO3/SrTiO3 Interfaces

TL;DR

This paper develops a model for magnetic and superconducting phenomena at LaAlO3/SrTiO3 interfaces, highlighting the roles of localized and itinerant electrons, spin-orbit coupling, and their interplay in producing unconventional superconductivity and potential Majorana states.

Contribution

It introduces a novel theoretical framework combining magnetic ordering and superconductivity at oxide interfaces, emphasizing the influence of spin-orbit coupling and electron interactions.

Findings

Magnetic ordering arises from the interplay of localized and itinerant electrons.

Superconductivity is modeled as random grains coupled to interface conduction.

Unconventional superconductivity may host Majorana fermions.

Abstract

We formulate a model for magnetic and superconducting ordering at LaAlO3/SrTiO3 interfaces containing both localized magnetic moments and itinerant electrons. Though these both originate in Ti 3d orbitals, the former may be due to electrons more tightly-bound to the interface while the latter are extended over several layers. Only the latter contribute significantly to metallic conduction and superconductivity. In our model, the interplay between the two types of electrons, which is argued to be ferromagnetic, combined with strong spin-orbit coupling of the itinerant electrons, leads to magnetic ordering. Furthermore, we propose a model for interfacial superconductivity, consisting of random superconducting grains in the bulk STO driven, via coupling to the interface conduction band, towards long-ranged or quasi-long-ranged order. Most interestingly, the magnetic order and strong spin orbit coupling can lead in this manner to unconventional interfacial superconductivity, yielding a possible realization of Majorana physics.