Magnetic frustration can give rise to intriguing ground states like quantum spin liquids and valance bond states. On 2D square lattices with S=1/2 or 1, such frustration can originate from incompatible Heisenberg exchange interactions, i.e., when antiferromagnetic J₂/J₁~0.5. Yet, it has been challenging to tune the frustration ratio towards this regime.

In a recent RIXS experiment, we studied spin excitations in spin-1 La₂NiO₄ films grown on various substrates. Modeling of the magnons shows that epitaxial strain acts as an effective tuning of the magnetic frustration in this system. These results offer a new route to explore the physics of frustrated magnetism.

This work has been published in Communications Physics (Biało, I.^✉, Martinelli, L., Wang, Q.^✉, Chang J. et al. Strain-tuned incompatible magnetic exchange-interaction in La₂NiO₄. https://doi.org/10.1038/s42005-024-01701-x). We are thankful to all collaborators.