Raman spectroscopy of the van der Waals altermagnet Co1/4NbSe2
Abstract
We investigate the influence of Co intercalation and altermagnetic order on the lattice dynamics of the layered compound Co1/4NbSe2. Polarization-resolved Raman spectroscopy, supported by density-functional theory, enables identification of six Raman-active phonons. Co intercalation drives a substantial reconstruction of the vibrational spectrum through zone folding of NbSe2 phonons, producing hybridized modes with mixed zone-center and zone-boundary character. Despite this, Co atoms do not participate in any Raman-active modes by symmetry, which is in marked contrast to related 1/3 compounds where intercalant modes do contribute to the Raman spectrum. Temperature-dependent Raman measurements across the altermagnetic transition show no discontinuities, which is consistent with magnetic fluctuations persisting above the Néel temperature. However, we find evidence for spin-phonon coupling in A1g symmetry modes owing to their out-of-plane Se displacements. Our work demonstrates the substantial impact of intercalation on the vibrational properties of transition metal dichalcogenides and the presence of spin-phonon interactions in a newly discovered altermagnetic material.
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BibTeX
@misc{balasundaram2026raman,
title = {{Raman spectroscopy of the van der Waals altermagnet Co$_1/4$NbSe$_2$}},
author = {Dushyanthini Balasundaram and Bishal Thapa and Resham Babu Regmi and Nirmal J. Ghimire and Igor I. Mazin and Patrick M. Vora},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2607.05616},
eprint = {2607.05616},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.05616},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Raman spectroscopy of the van der Waals altermagnet Co_1/4NbSe_2
AU - Dushyanthini Balasundaram
AU - Bishal Thapa
AU - Resham Babu Regmi
AU - Nirmal J. Ghimire
AU - Igor I. Mazin
AU - Patrick M. Vora
PY - 2026
DA - 2026/09/18
PB - arXiv
DO - 10.48550/arxiv.2607.05616
UR - https://arxiv.org/abs/2607.05616
AB - We investigate the influence of Co intercalation and altermagnetic order on the lattice dynamics of the layered compound Co_1/4NbSe_2. Polarization-resolved Raman spectroscopy, supported by density-functional theory, enables identification of six Raman-active phonons. Co intercalation drives a substantial reconstruction of the vibrational spectrum through zone folding of NbSe_2 phonons, producing hybridized modes with mixed zone-center and zone-boundary character. Despite this, Co atoms do not participate in any Raman-active modes by symmetry, which is in marked contrast to related 1/3 compounds where intercalant modes do contribute to the Raman spectrum. Temperature-dependent Raman measurements across the altermagnetic transition show no discontinuities, which is consistent with magnetic fluctuations persisting above the Néel temperature. However, we find evidence for spin-phonon coupling in A_1g symmetry modes owing to their out-of-plane Se displacements. Our work demonstrates the substantial impact of intercalation on the vibrational properties of transition metal dichalcogenides and the presence of spin-phonon interactions in a newly discovered altermagnetic material.
ER -