Ultra-Stable Ferrimagnetic Second-Order Topological Insulator in 2D Metal-Organic Framework

Fuente: arXiv
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Main Authors: Wang, Meijun, Zhong, Yong-An, Jin, Lei, Liu, Ying, Dai, Xuefang, Liu, Guodong, Zhang, Xiaoming
Format: Preprint
Published: 2025
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author Wang, Meijun
Zhong, Yong-An
Jin, Lei
Liu, Ying
Dai, Xuefang
Liu, Guodong
Zhang, Xiaoming
author_facet Wang, Meijun
Zhong, Yong-An
Jin, Lei
Liu, Ying
Dai, Xuefang
Liu, Guodong
Zhang, Xiaoming
contents Two-dimensional (2D) magnetic second-order topological insulators (SOTIs) exhibit distinct topological phases characterized by spin-polarized zero-dimensional (0D) corner states, which have garnered significant interest. However, 2D ferrimagnetic (FiM) SOTIs, particularly those that simultaneously exhibit ultra-stable corner states, are still lacking. Here, based on first-principles calculations and theoretical analysis, we reveal such SOTI state in a 2D metal-organic framework (MOF) material, Cr(pyz)2 (pyz = pyrazine). This material exhibits FiM ground state with an easy axis aligned along [001] direction. It hosts a nontrivial real Chern number in the spin-up channel, enabled by PT symmetry, with 0D corner states observable in disk. In contrast, the spin-down channel exhibits a trivial gapped bulk state. Notably, the topological corner states in monolayer Cr(pyz)2 show high robustness, even if the symmetries are broken by introducing defects, the corner states persist. We also considered other external perturbations, including uniaxial/biaxial strain, ligand rotation, and electric fields, the corner states still remain stable. Even more, the energy positions of the corner states are also nearly unchanged. This work is the first to identify ultra-stable FiM SOTI state in the MOF system, and provide an ideal platform for future experimental investigations and applications in spintronic devices.
format Preprint
id arxiv_https___arxiv_org_abs_2502_15257
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Ultra-Stable Ferrimagnetic Second-Order Topological Insulator in 2D Metal-Organic Framework
Wang, Meijun
Zhong, Yong-An
Jin, Lei
Liu, Ying
Dai, Xuefang
Liu, Guodong
Zhang, Xiaoming
Materials Science
Mesoscale and Nanoscale Physics
Two-dimensional (2D) magnetic second-order topological insulators (SOTIs) exhibit distinct topological phases characterized by spin-polarized zero-dimensional (0D) corner states, which have garnered significant interest. However, 2D ferrimagnetic (FiM) SOTIs, particularly those that simultaneously exhibit ultra-stable corner states, are still lacking. Here, based on first-principles calculations and theoretical analysis, we reveal such SOTI state in a 2D metal-organic framework (MOF) material, Cr(pyz)2 (pyz = pyrazine). This material exhibits FiM ground state with an easy axis aligned along [001] direction. It hosts a nontrivial real Chern number in the spin-up channel, enabled by PT symmetry, with 0D corner states observable in disk. In contrast, the spin-down channel exhibits a trivial gapped bulk state. Notably, the topological corner states in monolayer Cr(pyz)2 show high robustness, even if the symmetries are broken by introducing defects, the corner states persist. We also considered other external perturbations, including uniaxial/biaxial strain, ligand rotation, and electric fields, the corner states still remain stable. Even more, the energy positions of the corner states are also nearly unchanged. This work is the first to identify ultra-stable FiM SOTI state in the MOF system, and provide an ideal platform for future experimental investigations and applications in spintronic devices.
title Ultra-Stable Ferrimagnetic Second-Order Topological Insulator in 2D Metal-Organic Framework
topic Materials Science
Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2502.15257