Coherent transport in strongly correlated perovskite-manganite quantum wells

強相関ペロブスカイトマンガン鉱の量子井戸におけるコヒーレント伝導

遠藤 達朗*; 荒木 康史   ; 関 宗俊*; 田畑 仁*; 田中 雅明*; 大矢 忍*

Endo, Tatsuro*; Araki, Yasufumi; Seki, Munetoshi*; Tabata, Hitoshi*; Tanaka, Masaaki*; Oya, Shinobu*

Perovskite transition metal oxides (TMOs) are hallmark systems for studying electron correlations, with strong Coulomb interactions reaching the electron volt scale. Such interactions generally hinder coherent charge transport, limiting its observation to only moderately correlated TMOs. Among TMOs with strong electron correlations, the ferromagnetic perovskite manganite LaSrMnO (LSMO) has attracted significant attention for spintronics applications due to its half-metallic nature and robust ferromagnetism, with a Curie temperature above room temperature. In this Letter, we report the emergence of oscillatory conduction in tunnel diodes incorporating an epitaxial thin LSMO layer - a phenomenon not previously observed in strongly correlated oxides. The observed oscillations originate from discrete quantum-well states formed via quantum confinement, indicating coherent transport across the LSMO layer. These quantum-well states are quantitatively explained using a tight-binding model tailored for the electronic structure of LSMO. Our findings demonstrate that high- quality epitaxial perovskite manganites can sustain coherent transport, even in the presence of strong electron correlations, offering avenues for oxide-based quantum and spintronics devices.