title: Full determination of individual reconstructed atomic columns in intermixed heterojunctions.
abstract: Heterojunctions offer a tremendous opportunity for fundamental as well as applied research, ranging from the unique electronic phases in between oxides to the contact issues in semiconductor devices. Despite their pivotal roles, determining individual building atom of matter in heterojunctions is still challenging, especially for those between highly dissimilar structures, in which breaking of symmetry, chemistry, and bonds may give rise to complex reconstruction and intermixing at the junction. Here, we combine electron microscopy, spectroscopy, and first-principles calculations to determine individual reconstructed atomic columns and their charge states in a complex, multicomponent heterojunction between the delafossite CuScO2 and spinel MgAl2O4. The high resolution enables us to demonstrate that the reconstructed region can accommodate a highly selective intermixing of Cu cations at specific Sc cation sites with half atomic density, forming a complex ordered superstructure. Such ability to resolve reconstructed heterojunctions to the atomic dimensions helps elucidate atomistic mechanisms and discover novel properties with applications in a diverse range of scientific disciplines.
authors.affiliation: Advanced Institute for Materials Research, Tohoku University , 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
authors.forename: Zhongchang
authors.initials: Z
authors.lastname: Wang
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Saito
authors.forename: Chunlin
authors.initials: C
authors.lastname: Chen
authors.forename: Yuya
authors.initials: Y
authors.lastname: Matsubara
authors.forename: Kazunori
authors.initials: K
authors.lastname: Ueno
authors.forename: Masashi
authors.initials: M
authors.lastname: Kawasaki
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Ikuhara
keywords: CuScO2/MgAl2O4 interface; atomic reconstruction; density functional theory; ordered superstructure; transmission electron microscopy