Antiferromagnetic Ising Model on Inverse Perovskite Lattice

TL;DR

This study investigates the thermodynamic behavior of an antiferromagnetic Ising model on the inverse perovskite lattice, revealing unique zero-temperature criticality and complex phase transitions influenced by external fields and anisotropy.

Contribution

It provides the first detailed analysis of the inverse perovskite lattice's magnetic properties, highlighting its zero-temperature multicriticality and the effects of perturbations on phase transitions.

Findings

Degenerate ground state with large residual entropy.

External perturbations lift degeneracy and induce ordered phases.

Presence of 1/3 magnetization plateaus in the PDAF phase.

Abstract

We study thermodynamic properties of an antiferromagnetic Ising model on the inverse perovskite lattice by using Monte Carlo simulations. The lattice structure is composed of corner-sharing octahedra and contains three-dimensional geometrical frustration in terms of magnetic interactions. The system with the nearest-neighbor interactions alone does not exhibit any phase transition, leading to a degenerate ground state with large residual entropy. The degeneracy is lifted by an external magnetic field or by an anisotropy in the interactions. Depending on the anisotropy, they stabilize either a 3D ferrimagnetic state or a partially-disordered antiferromagnetic (PDAF) state with a dimensionality reduction to 2D. By the degeneracy-lifting perturbations, all the transition temperatures of these different ordered states continuously grow from zero, leaving an unusual zero-temperature critical point at the unperturbed point. Such a zero-temperature multicriticality is not observed in other frustrated structures such as face-centered cubic and pyrochlore. The transition to the PDAF state is represented by either the first- or second-order boundaries separated by tricritical lines, whereas the PDAF phase shows 1/3 magnetization plateaus.