Mechanically and electrically switchable triferroic altermagnet in a pentagonal FeO2 monolayer

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Main Authors: Guo, Deping, Dai, Jiaqi, Wang, Renhong, Wang, Cong, Ji, Wei
Format: Preprint
Published: 2025
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author Guo, Deping
Dai, Jiaqi
Wang, Renhong
Wang, Cong
Ji, Wei
author_facet Guo, Deping
Dai, Jiaqi
Wang, Renhong
Wang, Cong
Ji, Wei
contents Two-dimensional multiferroics promise low-power, multifunctional devices, yet the intrinsic coexistence and mutual control of three coupled ferroic orders in a single layer remains elusive. Here, we identify pentagonal monolayer FeO$_2$ as an intrinsic triferroic altermagnet where ferroelectric (FE), ferroelastic (FA), and altermagnetic (AM) orders coexist and are tightly coupled, accompanied by a competing antiferroelectric (AFE) phase using first-principles calculations. The sole presence of glide mirror $M_x$ symmetry in a FeO$_2$ sublayer, with the breaking of four-fold rotation $C_{4z}$ symmetry, induces in-plane vector ferroelectricity and twin-related ferroelastic strains. Both FE and AFE phases break combined parity - time symmetry and display sizable altermagnetic spin splitting with Néel temperatures over 200~K. Electric-field-induced rotation of the FE polarization reverses the sign of the spin splitting, while in-plane uniaxial strain triggers ferroelastic switching that simultaneously rotates the FE polarization vector by $90^\circ$ and reverses the AM state. These electric-field- and strain-mediated pathways interlink six distinct polarization states that can be selected purely by electric fields and/or mechanical strain. This work extends intrinsic triferroicity to pentagonal monolayers and outlines a symmetry-based route toward mechanically and electrically configurable altermagnetic spintronics.
format Preprint
id arxiv_https___arxiv_org_abs_2507_17247
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Mechanically and electrically switchable triferroic altermagnet in a pentagonal FeO2 monolayer
Guo, Deping
Dai, Jiaqi
Wang, Renhong
Wang, Cong
Ji, Wei
Materials Science
Computational Physics
Two-dimensional multiferroics promise low-power, multifunctional devices, yet the intrinsic coexistence and mutual control of three coupled ferroic orders in a single layer remains elusive. Here, we identify pentagonal monolayer FeO$_2$ as an intrinsic triferroic altermagnet where ferroelectric (FE), ferroelastic (FA), and altermagnetic (AM) orders coexist and are tightly coupled, accompanied by a competing antiferroelectric (AFE) phase using first-principles calculations. The sole presence of glide mirror $M_x$ symmetry in a FeO$_2$ sublayer, with the breaking of four-fold rotation $C_{4z}$ symmetry, induces in-plane vector ferroelectricity and twin-related ferroelastic strains. Both FE and AFE phases break combined parity - time symmetry and display sizable altermagnetic spin splitting with Néel temperatures over 200~K. Electric-field-induced rotation of the FE polarization reverses the sign of the spin splitting, while in-plane uniaxial strain triggers ferroelastic switching that simultaneously rotates the FE polarization vector by $90^\circ$ and reverses the AM state. These electric-field- and strain-mediated pathways interlink six distinct polarization states that can be selected purely by electric fields and/or mechanical strain. This work extends intrinsic triferroicity to pentagonal monolayers and outlines a symmetry-based route toward mechanically and electrically configurable altermagnetic spintronics.
title Mechanically and electrically switchable triferroic altermagnet in a pentagonal FeO2 monolayer
topic Materials Science
Computational Physics
url https://arxiv.org/abs/2507.17247