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arXiv · 2509.03988

Hubbard dimer physics and the magnetostructural transition in the correlated cluster material Nb$_3$Cl$_8$

Alberto Carta·Peter Mlkvik·Fabian Grahlow·Markus Ströbele·H. -Jürgen Meyer·Carl P. Romao·Nicola A. Spaldin·Claude Ederer
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Abstract

We present a combined computational and experimental study of Nb$_3$Cl$_8$, a correlated layered material containing Nb trimers, through the lens of competing intra- and intercluster interactions. Different proposed explanations for its magnetostructural transition such as charge disproportionation, antiferromagnetic quenching, and interlayer singlet formation are investigated in light of the various reported low-temperature structures. Our findings rule out the previously proposed charge-disproportionation, suggest an intricate interplay between Mott physics and the formation of interlayer singlets, and also hint at a possible explanation of the observed intratrimer scissoring distortion. We suggest that the physics of Nb$_3$Cl$_8$ should be understood in the context of weakly coupled Hubbard dimers.

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Alberto Carta, Peter Mlkvik, Fabian Grahlow, Markus Ströbele, H. -Jürgen Meyer, Carl P. Romao, Nicola A. Spaldin, Claude Ederer. 2025-09-04. Hubbard dimer physics and the magnetostructural transition in the correlated cluster material Nb$_3$Cl$_8$. https://arxiv.org/abs/2509.03988

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