Eightfold Degenerate Dirac Nodal Line in Collinear Antiferromagnet Mn${}_5$Si${}_3$

Abstract

We study the electronic, magnetic, and spin transport properties of the orthorhombic Mn${}_5$Si${}_3$ compound in the $AF2$ phase using symmetry analysis and ab-initio calculations. Our ground state energy calculations align with experimental observations, demonstrating that the collinear antiferromagnetic (AFM) order, with Néel vector in the [010] direction, is the most stable magnetic configuration both with and without spin-orbit coupling (SOC) in a bulk lattice geometry. We identified an unconventional eight-fold degenerate Dirac nodal line (DNL) close to the Fermi level, characterized by negligible SOC. This DNL is robustly protected by a unique combination of a pure-spin symmetry and a lattice symmetry together with magnetic space group symmetries. Upon introducing SOC, this degeneracy is reduced to two four-fold DNLs, being protected by the combination of time-reversal, partial translation and nonsymmorphic symmetries within the magnetic space group. We predict also a large intrinsic spin Hall conductivity (SHC) which correlates with the presence of SOC-induced splitting of these eight-fold degenerate DNLs near the Fermi level. These intriguing characteristics position collinear antiferromagnet Mn${}_5$Si${}_3$ as a compelling candidate for spintronic applications, particularly in the generation and detection of spin currents, while remaining compatible with modern silicon technology.

14 pages, 3 figures

References in corpus (14)

• Altermagnetism: spin-momentum locked phase protected by non-relativistic symmetries
• Study of Intrinsic Spin Hall Effect and Orbital Hall Effect in 4d- and 5d- Transition Metals
• Spin-group symmetry in magnetic materials with negligible spin-orbit coupling
• All Topological Bands of All Nonmagnetic Stoichiometric Materials
• Electric control of Dirac quasiparticles by spin-orbit torque in an antiferromagnet
• Landau Theory of Altermagnetism
• Spin Space Groups: Full Classification and Applications
• Non-symmorphic band degeneracy at the Fermi level in ZrSiTe
• Anisotropic spin Hall effect from first principles
• Switching of a large anomalous Hall effect between metamagnetic phases of a non-collinear antiferromagnet
• Altermagnetic variants in thin films of Mn5Si3
• Complex magnetic structure and spin waves of the noncollinear antiferromagnet Mn5Si3
• Spin-waves in the collinear antiferromagnetic phase of Mn$_\bf{5}$Si$_\bf{3}$
• An overview of the spin dynamics of antiferromagnetic Mn${}_5$Si${}_3$