Engineered Kondo screening and nonzero Berry phase in SrTiO3/LaTiO3/SrTiO3 heterostructures

TL;DR

This study investigates how varying the LaTiO3 layer thickness in SrTiO3/LaTiO3/SrTiO3 heterostructures influences magnetic interactions, revealing Kondo effects and nonzero Berry phases linked to interfacial spin-orbit coupling and magnetic orderings.

Contribution

It demonstrates the control of Kondo screening and Berry phase in oxide heterostructures through layer thickness, highlighting the role of spin-orbit coupling and symmetry breaking.

Findings

Kondo effect observed in thin LaTiO3 layers (n=2,10)

Nonzero Berry phase ({}) detected in thin layers

Suppression of Kondo effect in thicker layer (n=20)

Abstract

Controlling the interplay between localized spins and itinerant electrons at the oxide interfaces can lead to exotic magnetic states. Here we devise SrTiO3/LaTiO3/SrTiO3 heterostructures with varied thickness of the LaTiO3 layer (n monolayers) to investigate the magnetic interactions in the two-dimensional electron gas system. The heterostructures exhibit significant Kondo effect when the LaTiO3 layer is rather thin (n = 2, 10), manifesting the strong interaction between the itinerant electrons and the localized magnetic moments at the interfaces, while the Kondo effect is greatly inhibited when n = 20. Notably, distinct Shubnikov-de Haas oscillations are observed and a nonzero Berry phase of {\pi} is extracted when the LaTiO3 layer is rather thin (n = 2, 10), which is absent in the heterostructure with thicker LaTiO3 layer (n = 20). The observed phenomena are consistently interpreted as a result of sub-band splitting and symmetry breaking due to the interplay between the interfacial Rashba spin-orbit coupling and the magnetic orderings in the heterostructures. Our findings provide a route for exploring and manipulating nontrivial electronic band structures at complex oxide interfaces.