Exact nematic and mixed magnetic phases driven by competing orders on the pyrochlore lattice

Fuente: arXiv
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Main Authors: Francini, Niccolò, Schmidt, Lukas, Janssen, Lukas, Lozano-Gómez, Daniel
Format: Preprint
Published: 2025
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author Francini, Niccolò
Schmidt, Lukas
Janssen, Lukas
Lozano-Gómez, Daniel
author_facet Francini, Niccolò
Schmidt, Lukas
Janssen, Lukas
Lozano-Gómez, Daniel
contents Pyrochlore magnets are a paradigmatic example of three-dimensional frustrated systems and provide an excellent platform for studying a variety of exotic many-body phenomena, including spin liquids, nematic phases, fragmentation, and order by disorder. In recent years, increasing attention has been devoted to bilinear spin models on this lattice, where multiple magnetic phases can be degenerate in energy, often stabilizing unconventional magnetic states. In this work, we focus on one such model, parametrized by the interaction coupling $J_{z\pm}$, which defines a line in parameter space corresponding to the phase boundary between three distinct magnetic phases. Using a combination of analytical and numerical methods, we show that this model exhibits an order-by-disorder mechanism at low temperatures, giving rise to a \emph{mixed} magnetic phase. This represents the first realization of a $\mathbf{q}=0$ long-range-ordered phase in a pyrochlore magnet characterized by two distinct order parameters, which we denote as the $A_2 \oplus ψ_2$ phase. Furthermore, at $J_{z\pm} = 1/\sqrt{2}$, the model acquires a subextensive number of discrete symmetries, which preclude the stabilization of conventional long-range order and instead lead to the emergence of a novel nematic phase. We characterize this nematic phase, describe how its ground-state configurations are constructed, and analyze its stability at higher temperatures and under small deviations from $J_{z\pm} = 1/\sqrt{2}$.
format Preprint
id arxiv_https___arxiv_org_abs_2510_23704
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Exact nematic and mixed magnetic phases driven by competing orders on the pyrochlore lattice
Francini, Niccolò
Schmidt, Lukas
Janssen, Lukas
Lozano-Gómez, Daniel
Strongly Correlated Electrons
Statistical Mechanics
Pyrochlore magnets are a paradigmatic example of three-dimensional frustrated systems and provide an excellent platform for studying a variety of exotic many-body phenomena, including spin liquids, nematic phases, fragmentation, and order by disorder. In recent years, increasing attention has been devoted to bilinear spin models on this lattice, where multiple magnetic phases can be degenerate in energy, often stabilizing unconventional magnetic states. In this work, we focus on one such model, parametrized by the interaction coupling $J_{z\pm}$, which defines a line in parameter space corresponding to the phase boundary between three distinct magnetic phases. Using a combination of analytical and numerical methods, we show that this model exhibits an order-by-disorder mechanism at low temperatures, giving rise to a \emph{mixed} magnetic phase. This represents the first realization of a $\mathbf{q}=0$ long-range-ordered phase in a pyrochlore magnet characterized by two distinct order parameters, which we denote as the $A_2 \oplus ψ_2$ phase. Furthermore, at $J_{z\pm} = 1/\sqrt{2}$, the model acquires a subextensive number of discrete symmetries, which preclude the stabilization of conventional long-range order and instead lead to the emergence of a novel nematic phase. We characterize this nematic phase, describe how its ground-state configurations are constructed, and analyze its stability at higher temperatures and under small deviations from $J_{z\pm} = 1/\sqrt{2}$.
title Exact nematic and mixed magnetic phases driven by competing orders on the pyrochlore lattice
topic Strongly Correlated Electrons
Statistical Mechanics
url https://arxiv.org/abs/2510.23704