Engineered Kondo screening and nonzero Berry phase in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>SrTiO</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:mo>/</mml:mo><mml:msub><mml:mi>LaTiO</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:mo>/</mml:mo><mml:msub><mml:mi>SrTiO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math> heterostructures
Fang Yang, Zhenzhen Wang, Yonghe Liu, Shuai Yang, Ze Yu, Qichang An, Zhaoqing Ding, Fanqi Meng, Yanwei Cao, Qinghua Zhang, Lin Gu, Miao Liu, Yongqing Li, Jiandong Guo, Xiaoran Liu
Abstract
Controlling the interplay between localized spins and itinerant electrons at the oxide interfaces can lead to exotic magnetic states. Here we devise ${\mathrm{SrTiO}}_{3}/{\mathrm{LaTiO}}_{3}/{\mathrm{SrTiO}}_{3}$ heterostructures with varied thickness of the ${\mathrm{LaTiO}}_{3}$ layer ($n$ monolayers) to investigate the magnetic interactions in the two-dimensional electron gas system. The heterostructures exhibit significant Kondo effect when the ${\mathrm{LaTiO}}_{3}$ 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 \ensuremath{\pi} is extracted when the ${\mathrm{LaTiO}}_{3}$ layer is rather thin $(n =2,10)$, which is absent in the heterostructure with thicker ${\mathrm{LaTiO}}_{3}$ layer $(n =20)$. The observed phenomena are consistently interpreted as a result of subband 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.