Physics Colloquium

Can Antiferromagnetic Order Survive Lattice Melting?

Antiferromagnetism is usually tied to a crystal lattice, which provides the bipartite structure needed to define alternating order. But what becomes of antiferromagnetic order when the lattice itself melts? In this talk, I will discuss a two-dimensional colloidal system in which strong antiferromagnetic interactions qualitatively reshape the usual defect-mediated melting scenario, producing an intermediate tetratic phase between solid and liquid. I will show how antiferromagnetic structure can still be meaningfully characterized in this partially melted state, even though no conventional local order parameter sharply distinguishes it from a paramagnetic tetratic regime. Rather, the central question is whether one can consistently reconstruct the underlying bipartite structure, and hence a staggered magnetization, from the defect configuration itself. The result is a computational phase transition: a sharp change in the ability to infer correlations between distant spins. Along the way, I will highlight connections between lattice melting, topology, and ideas from quantum error correction.

Join via Zoom:
https://caltech.zoom.us/j/84497014003
Meeting ID: 844 9701 4003

The colloquium is held in Feynman Lecture Hall, 201 E. Bridge.