Magnetic-Field-Dependent Thermodynamic Properties of Square and Quadrupolar Artificial Spin Ice

TL;DR

This study combines simulations and experiments to explore how in-plane magnetic fields influence the thermodynamic properties and phase transitions of square and quadrupolar artificial spin ice systems, revealing diverse magnetic states.

Contribution

It provides the first comprehensive field-dependent thermodynamic maps of artificial spin ice, integrating Monte Carlo simulations with experimental magnetization noise measurements.

Findings

Identified multiple magnetic phases and transitions in ASI under varying magnetic fields.

Mapped the thermodynamic properties such as magnetization and specific heat across phase diagrams.

Validated simulation results with experimental magneto-optical measurements.

Abstract

Applied magnetic fields are an important tuning parameter for artificial spin ice (ASI) systems, as they can drive phase transitions between different magnetic ground states, or tune through regimes with high populations of emergent magnetic excitations (e.g., monopole-like quasiparticles). Here, using simulations supported by experiments, we investigate the thermodynamic properties and magnetic phases of square and quadrupolar ASI as a function of applied in-plane magnetic fields. Monte Carlo simulations are used to generate field-dependent maps of the magnetization, the magnetic specific heat, the thermodynamic magnetization fluctuations, and the magnetic order parameters, all under equilibrium conditions. These maps reveal the diversity of magnetic orderings and the phase transitions that occur in different regions of the phase diagrams of these ASIs, and are experimentally supported by magneto-optical measurements of the equilibrium "magnetization noise" in thermally-active ASIs.