Spin Dodecamer Formation in the Double-Exchange Spin Ice Model

TL;DR

This study uses Monte Carlo simulations to explore how geometrical frustration in the double-exchange spin ice model on a kagomé lattice leads to the formation of a unique dodecamer spin cluster order at low temperatures.

Contribution

It reveals the emergence of dodecamer spin clusters driven by kinetic energy and frustration in a metallic system with double-exchange interactions.

Findings

Dodecamer order appears at low temperatures for specific electron densities.

Cluster formation is driven by kinetic energy gain and frustration effects.

Cluster orders may be common in itinerant electron systems with frustrated fields.

Abstract

We investigated the double-exchange spin ice (DESI) model on a kagom\'e lattice by Monte Carlo simulation to study the effects of a geometrical frustration, and the mechanism that generates an ordered state in a metallic system. The DESI model on the kagom\'e lattice is a frustrated metallic system due to an effective ferromagnetic interaction between localized spins caused by the double-exchange (DE) mechanism and a uniaxial anisotropy for the localized spins. A dodecagonal spin cluster (named dodecamer), which consists of twelve localized spins, appears at low temperature when the number of particles per site $n \simeq 1/3 \sim 1/2$. Such a dodecamer order is driven by both the kinetic energy gain due to the DE mechanism and the geometrical frustration. We discuss that cluster orders, in general, may be a common feature in itinerant electron systems coupled with frustrated adiabatic fields.