Seminar announcement

Friday 27th June at 14:00pm – Seminar Room Louis Michel at CPHT, Ecole Polytechnique

 

Topological devil's step in a constrained kagome Ising antiferromagnet

 

Jeanne Colbois, CNRS and Institut Louis Neel, Grenoble

 

Despite their apparent simplicity, classical Ising models can give rise to exotic ground state phases in the presence of frustration (e.g., when antiferromagnetic pair interactions cannot be simultaneously minimized) [1]. The finite-temperature physics induced by such  macroscopically degenerate ground states can prove extremely rich, but, except at fine-tuned point, studying them with numerical or analytical methods can prove difficult. 

 

I will briefly describe how tensor network methods -- well known for their success in  the study of quantum spin systems -- can also help solve such classical statistical mechanics problems on a lattice [2,3]. As a case in point, I will discuss a surprising staircase behavior observed in the constrained limit of a farther-neighbor kagome Ising antiferromagnet. After recalling some key notions, I will argue that, unlike in standard Devil's staircases, the driving mechanism here is Kastelyn-like and leads to a staircase of topological origin [4].

 

[1] C. Lacroix, P. Mendels, and F. Mila, Introduction to Frustrated Magnetism: Materials, Experiments, Theory (2011)

[2] B. Vanhecke, J. Colbois et al, Solving Frustrated Ising models using tensor networks, Phys. Rev. Res, (2021)

[3] J. Colbois, B. Vanhecke et al, Partial lifting of degeneracy in the J1-J2-J3 Ising antiferromagnet on the kagome lattice, Phys. Rev. B (2022)

[4] A. Rufino, S. Nyckees, J. Colbois, and F. Mila, Topological devil's staircase in a constrained kagome Ising antiferromagnet, arXiv:2505.05899

 

 

Join Zoom Meeting

https://ecolepolytechnique.zoom.us/j/93995827714?pwd=P2rhTD85Lzf9Ex4BEmt...

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