Experimental realization of the ground state for the antiferromagnetic Ising model on a triangular lattice

TL;DR

This paper demonstrates an experimental setup using magnetic cylinders to realize and observe the ground state of the antiferromagnetic Ising model on a triangular lattice, revealing exotic phases and validating results with simulations.

Contribution

It introduces a novel magnetic platform to directly observe and study the ground state and frustrated behavior of the AFIT model, combining experiments with simulations and machine learning.

Findings

Observation of a curved stripe phase in the AFIT model

Successful experimental realization of the ground state configurations

Agreement between experimental results and theoretical simulations

Abstract

The antiferromagnetic Ising model on a triangular lattice (AFIT) exemplifies the most classical frustration system, arising from its triangular geometry that prevents all interactions from being simultaneously satisfied. Understanding geometric frustration in AFIT is crucial for advancing our knowledge of materials science and complex phases of matter. Here, we present a simple platform to study AFIT by arranging cylindrical magnets in vertical cavities of a triangular lattice, where magnets can slide along the cavity axis and stabilize either at the bottom or at the top of the cavity, analogous to the bistability of the Ising spin. The strong interactions of the magnets and the unique growing process allow the frustrated behavior and its ground state configurations to be directly observed. Notably, we observe a curved stripe phase, which is exotic to the Ising model. An effective thermalization process is developed to minimize the interaction energy, facilitating the evolution of various magnetic states, thereby visually realizing the ground state antiferromagnetic Ising model. Theoretical simulations and machine learning are performed concurrently to reveal the ground state and its evolution under effective thermal fluctuations, which are remarkably consistent with experimental results. Our system provides a unique platform to study frustrated systems and pave the way for future explorations in complex geometries.