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

Controlling the interplay between localized spins and itinerant electrons at\nthe oxide interfaces can lead to exotic magnetic states. Here we devise\nSrTiO3/LaTiO3/SrTiO3 heterostructures with varied thickness of the LaTiO3 layer\n(n monolayers) to investigate the magnetic interactions in the two-dimensional\nelectron gas system. The heterostructures exhibit significant Kondo effect when\nthe LaTiO3 layer is rather thin (n = 2, 10), manifesting the strong interaction\nbetween the itinerant electrons and the localized magnetic moments at the\ninterfaces, while the Kondo effect is greatly inhibited when n = 20. Notably,\ndistinct Shubnikov-de Haas oscillations are observed and a nonzero Berry phase\nof {\\pi} is extracted when the LaTiO3 layer is rather thin (n = 2, 10), which\nis absent in the heterostructure with thicker LaTiO3 layer (n = 20). The\nobserved phenomena are consistently interpreted as a result of sub-band\nsplitting and symmetry breaking due to the interplay between the interfacial\nRashba spin-orbit coupling and the magnetic orderings in the heterostructures.\nOur findings provide a route for exploring and manipulating nontrivial\nelectronic band structures at complex oxide interfaces.\n