An unconventional pathway to correlate the octahedral tilt coupling and spin-orbit reconstruction at oxide interfaces.

Dey, Jayjit Kumar; Jagadish, Koushik; Bandyopadhyay, Arka; Chowdhury, Sourav; Hoesch, Moritz; Valvidares, Manuel; Ahlawat, Anju; Afaneh, Feras et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

The direct experimental probing and detailed imaging of octahedral tilt, along with the control of magnetic ground state and spin-orbit occupancies in an artificially engineered heterointerface through the strain manipulation via interface engineering, is the long-standing challenging issue addressed here. We introduce an innovative methodology to measure the projected O-O-O angles (O-O-O<sub>proj</sub>) between the neighboring in-plane BO<sub>6</sub> octahedra of perovskite oxide (ABO<sub>3</sub>), demonstrating a precise quantification of strain-manipulated octahedral tilt in atomically engineered LaCoO<sub>3</sub> (LCO)/La<sub>0.7</sub>Sr<sub>0.3</sub>MnO<sub>3</sub> (LSMO) bilayer interfaces. The pronounced octahedral tilt on SrTiO<sub>3</sub> (STO) substrate (tensile strain) compared to LaAlO<sub>3</sub> (LAO) substrate (compressive strain) correlates to the magnetism especially within the framework of bond angle geometry and spin-charge-orbital reconstructions, contrasting with individual single-phase films. Interfacial orbital reconstruction, Co/Mn antiferromagnetic coupling and their strain manipulation are quantified through X-ray linear dichroism (XLD) and X-ray magnetic circular dichroism (XMCD) measurements, further confirmed by both molecular orbital theory and Goodenough-Kanamori-Anderson rules. First principles calculations unveil a higher (lower) magnetic moment of individual magnetic atoms with tensile (compressive) strain, including unusual interfacial antiferromagnetism arising d-orbital occupations, and bond angle geometry. This endeavor paves a potential method to manipulate the octahedral tilt to tailor emergent phenomena at heterointerfaces via atomically precise strain-interface engineering.