Ferromagnetism on an atom-thick & extended 2D metal-organic coordination network

TL;DR

Researchers created a 2D metal-organic network showing ferromagnetism with high magnetic properties and a Curie temperature of 35K.

Contribution

Demonstrated experimentally feasible 2D ferromagnetism in atom-thin metal-organic coordination networks.

Findings

Achieved ferromagnetism with coercive fields over 2 Tesla and a Curie temperature of ~35 K.

Magnetic properties arise from exchange interactions mediated by molecular linkers.

Only ~5% of the monolayer consists of Fe atoms, yet extended cooperative magnetism is observed.

Abstract

Ferromagnetism is the collective alignment of atomic spins that retain a net magnetic moment below the Curie temperature, even in the absence of external magnetic fields. Reducing this fundamental property into strictly two-dimensions was proposed in metal-organic coordination networks, but thus far has eluded experimental realization. In this work, we demonstrate that extended, cooperative ferromagnetism is feasible in an atomically thin two-dimensional metal-organic coordination network, despite only ≈ 5% of the monolayer being composed of Fe atoms. The resulting ferromagnetic state exhibits an out-of-plane easy-axis square-like hysteresis loop with large coercive fields over 2 Tesla, significant magnetic anisotropy, and persists up to TC ≈ 35 K. These properties are driven by exchange interactions mainly mediated by the molecular linkers. Our findings resolve a two decade search for ferromagnetism in two-dimensional metal-organic coordination networks.

Despite having all the ingredients required for the formation of two-dimensional ferromagnetism, achieving such a magnetic state in atomically thin metal-organic coordination networks has proved to be a persistent challenge. Here, Lobo-Checa et al demonstrate 2Dferromagnetism in a self-assembled network, exhibiting coercive fields over 2 Tesla and a Curie temperature of 35K.

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