Strong Ferromagnetism Achieved via Breathing Lattices in Atomically Thin Cobaltites

TL;DR

This paper demonstrates a method to preserve strong ferromagnetism in atomically thin LaCoO3 layers by engineering heterointerfaces with SrCuO2, leading to enhanced magnetic properties suitable for spintronic devices.

Contribution

It introduces a novel approach using breathing lattice structures and interface engineering to maintain and enhance ferromagnetism in ultra-thin oxide layers.

Findings

Achieved large magnetic moment (0.5 μB/Co) in monolayer LaCoO3.

Observed Curie temperature of 75 K in atomically thin layers.

Linked structural distortions to enhanced spin states and magnetic ordering.

Abstract

Low-dimensional quantum materials that remain strongly ferromagnetic down to mono layer thickness are highly desired for spintronic applications. Although oxide materials are important candidates for next generation of spintronic, ferromagnetism decays severely when the thickness is scaled to the nano meter regime, leading to deterioration of device performance. Here we report a methodology for maintaining strong ferromagnetism in insulating LaCoO3 (LCO) layers down to the thickness of a single unit cell. We find that the magnetic and electronic states of LCO are linked intimately to the structural parameters of adjacent "breathing lattice" SrCuO2 (SCO). As the dimensionality of SCO is reduced, the lattice constant elongates over 10% along the growth direction, leading to a significant distortion of the CoO6 octahedra, and promoting a higher spin state and long-range spin ordering. For atomically thin LCO layers, we observe surprisingly large magnetic moment (0.5 uB/Co) and Curie temperature (75 K), values larger than previously reported for any mono layer oxide. Our results demonstrate a strategy for creating ultra thin ferromagnetic oxides by exploiting atomic hetero interface engineering,confinement-driven structural transformation, and spin-lattice entanglement in strongly correlated materials.