Anisotropic Spin Ice on a Breathing Pyrochlore Lattice

Fuente: arXiv
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Autori principali: Isbrandt, Gloria, Pollmann, Frank, Knap, Michael
Natura: Preprint
Pubblicazione: 2025
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author Isbrandt, Gloria
Pollmann, Frank
Knap, Michael
author_facet Isbrandt, Gloria
Pollmann, Frank
Knap, Michael
contents Spin ice systems represent a prime example of constrained spin systems and exhibit rich low-energy physics. In this study, we explore how introducing a tunable anisotropic spin coupling to the conventional Ising spin ice Hamiltonian on the breathing pyrochlore lattice affects the ground state properties of the system. Significant changes are observed in the ground state structure, reflected in the spin structure factor and in a reduction of residual entropy at low temperatures. We theoretically uncover a rich phase diagram by varying the anisotropy and demonstrate how this modification reduces the ground state degeneracy across different phases. Numerical simulations reveal that, at sufficiently low temperatures, the system either undergoes a crossover into a constrained spin ice manifold, characterized by an entropy density that drops below the Pauling entropy of conventional spin ice, or a phase transition into a symmetry-broken state, depending on the perturbations. Additionally, we compute the spin structure factors for the anisotropic model and compare these results to analytical predictions from a large-$N$ expansion, finding good agreement. This work develops the understanding of spin ice in anisotropic limits, which may be experimentally realized by strain, providing, among others, key signatures in entropy and specific heat.
format Preprint
id arxiv_https___arxiv_org_abs_2505_00767
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Anisotropic Spin Ice on a Breathing Pyrochlore Lattice
Isbrandt, Gloria
Pollmann, Frank
Knap, Michael
Strongly Correlated Electrons
Spin ice systems represent a prime example of constrained spin systems and exhibit rich low-energy physics. In this study, we explore how introducing a tunable anisotropic spin coupling to the conventional Ising spin ice Hamiltonian on the breathing pyrochlore lattice affects the ground state properties of the system. Significant changes are observed in the ground state structure, reflected in the spin structure factor and in a reduction of residual entropy at low temperatures. We theoretically uncover a rich phase diagram by varying the anisotropy and demonstrate how this modification reduces the ground state degeneracy across different phases. Numerical simulations reveal that, at sufficiently low temperatures, the system either undergoes a crossover into a constrained spin ice manifold, characterized by an entropy density that drops below the Pauling entropy of conventional spin ice, or a phase transition into a symmetry-broken state, depending on the perturbations. Additionally, we compute the spin structure factors for the anisotropic model and compare these results to analytical predictions from a large-$N$ expansion, finding good agreement. This work develops the understanding of spin ice in anisotropic limits, which may be experimentally realized by strain, providing, among others, key signatures in entropy and specific heat.
title Anisotropic Spin Ice on a Breathing Pyrochlore Lattice
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2505.00767