Mechanism for lifting the degeneracy in the double-exchange spin ice model on a kagom\'e lattice: Dodecamer formation

TL;DR

This paper explores how a specific spin cluster state forms in a frustrated electron system on a kagome lattice, lifting degeneracy through a transition identified by Monte Carlo simulations.

Contribution

It introduces a mechanism for degeneracy lifting via dodecamer formation in the double-exchange spin ice model on a kagome lattice, supported by simulation data.

Findings

Identification of a double-peak specific heat structure.

Observation of a transition to a dodecamer spin cluster state.

Correlation between dodecamer formation and degeneracy lifting.

Abstract

We investigated the double-exchange spin ice model on a kagom\'e lattice by Monte Carlo simulation in order to study a mechanism for lifting the degeneracy in frustrated electron systems. We show specific heat and vector spin chirality data on a finite lattice. Specific heat has a double-peak structure: A broad peak and a sharp peak are at $k_{\rm B}T/t \sim 0.15$ and 0.015, respectively, where $t$ is the transfer integral of electrons. The broad peak corresponds to a crossover to the spin ice-like state, on the other hand, the sharp one a transition to a dodecagonal spin cluster (dodecamer) state. We discuss the interplay between the formation of the dodecamer state and the lifting of the macroscopic degeneracy.