Spin-resolved band structure characterization for the altermagnetic candidate CoNb3S6.

A newly reported magnetic phase – known as altermagnetism – has been proposed theoretically. These materials present features characteristic from both ferromagnets (strong time-reversal symmetry breaking and spin-polarized band structures) and antiferromagnets (zero net magnetic order), and show a strong potential for technological applications due to their robustness and compatibility with other strongly correlated materials (like superconductors).

Two main strategies have been pursued experimentally to prove the existence of this phase: (i) spin-resolved ARPES and (ii) magneto-transport measurements (by the observation of anomalous Hall effect). Only a few theoretically proposed materials – mainly thin films grown by MBE (MnTe, CrSb) – have been confirmed as altermagnets thanks to the direct observation of a band splitting. In this proposal, we aim to characterize by spin-resolved ARPES measurements the spin-polarized band structure of the quasi-2D altermagnetic candidate CoNb3S6. This antiferromagnetic material (TN = 27.5 K) can be exfoliated as a result of its layered nature (Co atoms inserted between NbS2 layers), providing very clean surfaces to study its electronic band structure.

We have successfully synthesised and characterized – by means of standard chemical and magnetic techniques, as well as through a magneto-transport approach – the proposed material, as well as some preliminary ARPES results at LOREA with linear horizontal and vertical polarised light at different photon energies (between 40 eV y 100 eV). Our results show a clear band structure, which constitutes a good starting point to further characterize the system, where we expect to observe spin-polarised bands in at least one of the proposed Brillouin high-symmetry points.