Near room-temperature magnetic nodal-line semiconductors in technetium-based self-intercalated van der Waals ferrimagnets

Abstract Magnetic nodal-line semiconductors, characterized by colossal magnetoresistance due to the lifting of spin orientation-dependent topological band degeneracy, hold great potential for advanced spintronic applications. However, a key challenge for the practical use of such topological magnets is their low magnetic transition temperature ( T C ). Through first-principles calculations, we identify the self-intercalated van der Waals ferrimagnet Tc 3 Si 2 Te 6 as a high- T C (~268 K) magnetic nodal-line semiconductor. Furthermore, we find that magnetic nodal-line semiconductors can exist in dually doped Tc 3 (Si 1- α Y α ) 2 (Te 1- β Z β ) 6 ( Y = Ge and Sn; Z = S and Se) over a broad range of α and β . Particularly, Tc 3 (Si 0.05 Ge 0.95 ) 2 (Te 0.70 Se 0.30 ) 6 is shown to be a near room-temperature magnetic nodal-line semiconductor with a sizable band gap. Our findings suggest Tc-based self-intercalated van der Waals ferrimagnets are promising magnetic nodal-line semiconductors for practical applications in spintronic devices.