Ferromagnetism is the collective alignment of atomic spins that retain a net magnetic moment below the Curie temperature, even in the absence of externalmagnetic 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 squarelike hysteresis loop with large coercive fields over 2 Tesla, significant magnetic anisotropy, and persists up to Tc ≈ 35 K (see Fig. 2). These properties are driven by exchange interactions mainly mediated by the molecular linkers that we explain with theoretical calculations. Our findings resolve a two-decade search for ferromagnetism in two-dimensional metal-organic coordination networks.

Resumen del trabajo presentado a la XXXIX Bienal de la Real Sociedad Española de Física, celebrada en Donostia-San Sebastián del 15 al 19 de julio de 2024.

Peer reviewed