Dimensionality-Driven Electronic and Orbital Transitions Mediating Interfacial Magnetism in LaNiO3/CaMnO3 Observed In Situ

TL;DR

This study investigates how reducing LaNiO3 thickness in LaNiO3/CaMnO3 superlattices induces a metal-insulator transition, orbital changes, and suppression of interfacial magnetism, revealing tunable electronic-magnetic coupling.

Contribution

It demonstrates the direct link between electronic confinement and magnetic properties in oxide heterostructures using combined experimental and theoretical methods.

Findings

Reducing LaNiO3 thickness causes a metal-insulator transition.

Orbital polarization crossover occurs in ultrathin LaNiO3.

Interfacial Mn magnetic moment is suppressed by electronic confinement.

Abstract

Emergent magnetic states at oxide interfaces arise from the interplay of charge transfer, orbital reconstruction, and dimensional confinement, offering a route to engineered correlated-electron behavior in nanoscale spintronic materials. Here, we combine in situ synthesis, polarization-dependent angle-resolved photoelectron spectroscopy, X-ray magnetic circular dichroism, and first-principles electronic-structure calculations to investigate LaNiO3/CaMnO3 superlattices. We show that reducing the LaNiO3 thickness drives a metal-insulator transition accompanied by loss of electronic coherence and an orbital-polarization crossover in the ultrathin limit. These changes weaken charge transfer across the interface and suppress the interfacial Mn magnetic moment in CaMnO3, revealing that the emergent ferromagnetic state is directly governed by electronic confinement in LaNiO3. The insulating state and orbital reconstruction are reproduced by density functional theory combined with dynamical mean-field theory. Together, these results establish a direct and tunable coupling among electronic, orbital, and magnetic degrees of freedom in oxide heterostructures.