Large peaks in the entropy of the diluted nearest-neighbor spin-ice model on the pyrochlore lattice in a [111] magnetic field

TL;DR

This study investigates the residual entropy peaks in diluted spin-ice models on pyrochlore, kagome, and triangular lattices under magnetic fields, revealing degeneracy at specific crossover points and the effects of dilution.

Contribution

It introduces a detailed analysis of entropy peaks in diluted spin-ice and related models under magnetic fields, highlighting the degeneracy and plateau phenomena across different lattice types.

Findings

Large entropy peaks at specific crossover fields.

Degeneracy associated with magnetization plateaus.

Dilution influences the entropy and plateau structure.

Abstract

We study the residual entropy of the nearest-neighbor spin-ice model in a magnetic field along the [111] direction using the Wang-Landau Monte Carlo method, with a special attention to dilution effects. For a diluted model, we observe a stepwise decrease of the residual entropy as a function of the magnetic field, which is consistent with the finding of the five magnetization plateaus in a previous replica-exchange Monte Carlo study by Peretyatko {\it et al.} [Phys. Rev. B {\bf 95}, 144410 (2017)]. We find large peaks of the residual entropy due to the degeneracy at the crossover magnetic fields, $h_c/J$ = 0, 3, 6, 9, and 12, where $h$ and $J$ are the magnetic field and the exchange coupling, respectively. In addition, we also study the residual entropy of the diluted antiferromagnetic Ising models in a magnetic field on the kagome and triangular lattices. We again observe large peaks of the residual entropy, which are associated with multiple magnetization plateaus for the diluted model. Finally, we discuss the interplay of dilution and magnetic fields in terms of the residual entropy.