Termination-dependent surface Fermiology in the intercalated altermagnet CoNb 4 Se 8
Abstract
Altermagnets have recently gained attention for hosting symmetry-enforced spin-split bands despite zero net magnetization. Angle-resolved photoelectron spectroscopy (ARPES) offers direct access to their electronic structure. However, the intrinsic surface sensitivity of this technique complicates the identification of the observed features: Surface states can be misinterpreted as the spin-split counterpart of bulk bands. This issue becomes particularly relevant for layered intercalated systems, where micrometer-sized domains with distinct terminations often coexist on a cleaved surface. We discuss this scenario for CoNb 4 Se 8 , one of the first established layered altermagnets. Supported by density functional theory calculations, we employ micro-ARPES to probe individual domains and reveal two contrasting surface terminations. We identify Co-and Se-terminated domains with characteristic surface states arising from bulk-surface connectivity of the material. Our work shows that termination-dependent surface contributions are essential for the reliable spectroscopic identification of altermagnetism and for assessing its presence across the family of layered materials.
Versions
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BibTeX
@article{forcella2026terminationdependent,
title = {{Termination-dependent surface Fermiology in the intercalated altermagnet CoNb 4 Se 8}},
author = {Pietro Maria Forcella and Alessandro de Vita and Matthew Watson and Sammar Tayyab and Chiara Bigi and Iulia Cojocariu and Marcin Szpytma and Matteo Jugovac and Andrea Locatelli and Tevfik Onur Menteş and My Bang Petersen and Paolo Moras and Polina Sheverdyaeva and Christopher Candelora and Ilija Zeljkovic and Federico Motti and Jill a Miwa and Vincent Polewczyk and Matthieu Jamet and Matteo Calandra and Younghun Hwang and Davide Romanin and Federico Mazzola},
journal = {Nano Letters},
year = {2026},
month = oct,
doi = {10.1021/acs.nanolett.6c01819},
eprint = {2610.23375},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05820462v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Termination-dependent surface Fermiology in the intercalated altermagnet CoNb 4 Se 8
AU - Pietro Maria Forcella
AU - Alessandro de Vita
AU - Matthew Watson
AU - Sammar Tayyab
AU - Chiara Bigi
AU - Iulia Cojocariu
AU - Marcin Szpytma
AU - Matteo Jugovac
AU - Andrea Locatelli
AU - Tevfik Onur Menteş
AU - My Bang Petersen
AU - Paolo Moras
AU - Polina Sheverdyaeva
AU - Christopher Candelora
AU - Ilija Zeljkovic
AU - Federico Motti
AU - Jill a Miwa
AU - Vincent Polewczyk
AU - Matthieu Jamet
AU - Matteo Calandra
AU - Younghun Hwang
AU - Davide Romanin
AU - Federico Mazzola
PY - 2026
DA - 2026/10/16
JO - Nano Letters
DO - 10.1021/acs.nanolett.6c01819
UR - https://hal.science/hal-05820462v1
AB - Altermagnets have recently gained attention for hosting symmetry-enforced spin-split bands despite zero net magnetization. Angle-resolved photoelectron spectroscopy (ARPES) offers direct access to their electronic structure. However, the intrinsic surface sensitivity of this technique complicates the identification of the observed features: Surface states can be misinterpreted as the spin-split counterpart of bulk bands. This issue becomes particularly relevant for layered intercalated systems, where micrometer-sized domains with distinct terminations often coexist on a cleaved surface. We discuss this scenario for CoNb 4 Se 8 , one of the first established layered altermagnets. Supported by density functional theory calculations, we employ micro-ARPES to probe individual domains and reveal two contrasting surface terminations. We identify Co-and Se-terminated domains with characteristic surface states arising from bulk-surface connectivity of the material. Our work shows that termination-dependent surface contributions are essential for the reliable spectroscopic identification of altermagnetism and for assessing its presence across the family of layered materials.
SN - 1530-6984
SN - 1530-6992
ER -