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TT: Fachverband Tiefe Temperaturen
TT 54: Correlated Electrons: Charge Order
TT 54.7: Vortrag
Freitag, 21. März 2025, 11:00–11:15, H33
Fingerprints of a Charge Ice State in the Doped Mott Insulator Nb3Cl8 — •Evgeny Stepanov — CNRS, Ecole Polytechnique
Monolayer Nb3Cl8 is a textbook example of a Mott insulator [1,2]. However, little is known about its characteristics, particularly in doped regimes where the strong local correlations responsible for the Mott state are competing with significant spatial collective electronic fluctuations.
Our many-body calculations suggest that monolayer Nb3Cl8 undergoes phase separation (PS) upon doping, driven by the emergence of a charge ice state [3]. In close proximity to the PS, the charge susceptibility dramatically increases and displays a distinctive bow-tie pattern in momentum space, resembling the form of magnetic susceptibility observed in spin ice states. At the same time, the effective exchange interaction between charge densities undergoes a striking transformation, acquiring a power-law dependence in real space. This dependence is reminiscent of hydrogen bonding interactions in water and serves as a hallmark of spin ice states when applied to spin degrees of freedom. These findings allow us to associate the observed PS with a charge ice state, characterized by a remarkable power-law dependence of correlations between electronic densities in real space.
While spin ice states were first experimentally realized in 1997 by Harris et al. [4], an analogue for charge degrees of freedom has remained elusive until now. Our work not only provides a theoretical description of the charge ice state but also offers compelling evidence that this novel phase can be realized in a real material.
[1] Nano Lett. 22, 4596 (2022);
[2] PRX 13, 041049 (2023);
[3] arXiv:2405.19114;
[4] PRL 79, 2554 (1997).
Keywords: charge ice state; phase separation; doped Mott insulators; collective electronic effects; many-body calculations