Altermagnets (AMs) are a new class of magnetic materials that combine the beneficial spintronics properties of ferromagnets and antiferromagnets, garnering significant attention recently. Here, we have identified altermagnetism in a layered intercalated transition metal diselenide, CoNb4Se8, which crystallizes with an ordered sublattice of intercalated Co atoms between NbSe2 layers. Single crystals are synthesized, and the structural characterizations are performed using single crystal diffraction and scanning tunneling microscopy. Magnetic measurements reveal easy-axis antiferromagnetism below 168 K. Density functional theory (DFT) calculations indicate that A-type antiferromagnetic ordering with easy-axis spin direction is the ground state, which is verified through single crystal neutron diffraction experiments. Electronic band structure calculations in this magnetic state display spin-split bands, confirming altermagnetism in this compound. The layered structure of CoNb4Se8 presents a promising platform for testing various predicted properties associated with altermagnetism.
@article{arxiv.2408.08835,
title = {Altermagnetism in the layered intercalated transition metal dichalcogenide CoNb$_4$Se$_8$},
author = {Resham Babu Regmi and Hari Bhandari and Bishal Thapa and Yiqing Hao and Nileema Sharma and James McKenzie and Xinglong Chen and Abhijeet Nayak and Mohamed El Gazzah and Bence Gábor Márkus and László Forró and Xiaolong Liu and Huibo Cao and J. F. Mitchell and I. I. Mazin and Nirmal J. Ghimire},
journal= {arXiv preprint arXiv:2408.08835},
year = {2026}
}