Magnetoelastic honeycomb fragmentation in VI$_{3}$

Fuente: arXiv
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Main Authors: Shen, Enlin, Popescu, Tiberiu I., Gora, Nishwal, Kaur, Guratinder, Chan, Edmond, Lane, Harry, Rodriguez-Rivera, Jose A., Xu, Guangyong, Gehring, Peter M., Ewings, Russell A., Fitch, Andy N., Stock, Chris
Format: Preprint
Published: 2025
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author Shen, Enlin
Popescu, Tiberiu I.
Gora, Nishwal
Kaur, Guratinder
Chan, Edmond
Lane, Harry
Rodriguez-Rivera, Jose A.
Xu, Guangyong
Gehring, Peter M.
Ewings, Russell A.
Fitch, Andy N.
Stock, Chris
author_facet Shen, Enlin
Popescu, Tiberiu I.
Gora, Nishwal
Kaur, Guratinder
Chan, Edmond
Lane, Harry
Rodriguez-Rivera, Jose A.
Xu, Guangyong
Gehring, Peter M.
Ewings, Russell A.
Fitch, Andy N.
Stock, Chris
contents The discovery of ordered magnetism in two-dimensional van der Waals materials at the monolayer limit challenges the Mermin-Wagner theorem, which forbids spontaneous breaking of continuous symmetries in two dimensions at finite temperatures. The persistence of static magnetism in low-dimensions is fundamentally influenced by magnetic anisotropy and the local single-ion crystalline electric field. Crucially, spin-orbit coupling connects the structural properties with spin degrees of freedom. We investigate the magnetic single-ion properties in the van der Waals magnet VI$_3$. Utilizing neutron and x-ray diffraction, we map out the symmetry breaking phase transitions and argue for a single structural transition at T$_S \sim$ 80 K, driven by an orbital degeneracy, followed by a ferromagnetic transition at a lower temperature, T$_C \sim$ 50 K. Through a comparative analysis of samples prepared under varying conditions, we suggest that lower temperature transitions reported near $\sim$ 30 K are not intrinsic to VI$_{3}$. A group theoretical analysis suggests a structural transition from rhombohedral $R\overline{3}$ to triclinic $P\overline{1}$ or $P1$. This transition is significant as it suggests the formation of two distinct crystallographyically inequivalent V$^{3+}$ sites, each with distinct spin-orbital properties. Neutron spectroscopy provides evidence for dominant magnetic exchange coupling only between symmetry-equivalent sites in the triclinc unit cell. We suggest this breaks up the low-temperature honeycomb VI$_3$ lattice into two interpenetrating approximately hexagonal planes resulting in a fragmentated honeycomb. Our findings highlight the critical role of magnetoelastic coupling in determining the magnetic and structural phases in two-dimensional van der Waals magnets.
format Preprint
id arxiv_https___arxiv_org_abs_2512_20240
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Magnetoelastic honeycomb fragmentation in VI$_{3}$
Shen, Enlin
Popescu, Tiberiu I.
Gora, Nishwal
Kaur, Guratinder
Chan, Edmond
Lane, Harry
Rodriguez-Rivera, Jose A.
Xu, Guangyong
Gehring, Peter M.
Ewings, Russell A.
Fitch, Andy N.
Stock, Chris
Materials Science
Strongly Correlated Electrons
The discovery of ordered magnetism in two-dimensional van der Waals materials at the monolayer limit challenges the Mermin-Wagner theorem, which forbids spontaneous breaking of continuous symmetries in two dimensions at finite temperatures. The persistence of static magnetism in low-dimensions is fundamentally influenced by magnetic anisotropy and the local single-ion crystalline electric field. Crucially, spin-orbit coupling connects the structural properties with spin degrees of freedom. We investigate the magnetic single-ion properties in the van der Waals magnet VI$_3$. Utilizing neutron and x-ray diffraction, we map out the symmetry breaking phase transitions and argue for a single structural transition at T$_S \sim$ 80 K, driven by an orbital degeneracy, followed by a ferromagnetic transition at a lower temperature, T$_C \sim$ 50 K. Through a comparative analysis of samples prepared under varying conditions, we suggest that lower temperature transitions reported near $\sim$ 30 K are not intrinsic to VI$_{3}$. A group theoretical analysis suggests a structural transition from rhombohedral $R\overline{3}$ to triclinic $P\overline{1}$ or $P1$. This transition is significant as it suggests the formation of two distinct crystallographyically inequivalent V$^{3+}$ sites, each with distinct spin-orbital properties. Neutron spectroscopy provides evidence for dominant magnetic exchange coupling only between symmetry-equivalent sites in the triclinc unit cell. We suggest this breaks up the low-temperature honeycomb VI$_3$ lattice into two interpenetrating approximately hexagonal planes resulting in a fragmentated honeycomb. Our findings highlight the critical role of magnetoelastic coupling in determining the magnetic and structural phases in two-dimensional van der Waals magnets.
title Magnetoelastic honeycomb fragmentation in VI$_{3}$
topic Materials Science
Strongly Correlated Electrons
url https://arxiv.org/abs/2512.20240