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arXiv · 1609.06916

Topological Gapless Phases in Non-Symmorphic Antiferromagnets

Wojciech Brzezicki·Mario Cuoco
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Abstract

Topologically protected fermionic quasiparticles occur in metals with band degeneracy as a consequence of band structure topology. Here we unveil topological semimetal and metal phases in a variety of non-symmorphic collinear antiferromagnets with glide reflection symmetry, a combination of mirror and half-lattice translation. We find gapless phases with Dirac points having multiple symmetry-protection as well as electronic structures with triple and quadruple band-crossing points. Glide semimetal is shown to be converted into a topological phase with non-trivial $\mathbb{Z}_2$ topological charges at the Dirac points due to inversion and time-inversion symmetry combination. More striking is the emergence of a hidden non-unitary relation between the states in the glide sectors that provide a general mechanism to get multiple band touching points. The split Fermi points uncover a $\mathbb{Z}_2$ protection that drives the changeover of the multiple-degenerate gapless phase into a topological metal built from their connection through distinct Fermi lines. Besides a new perspective of ordered states in complex materials, our findings indicate that novel topological gapless phases and edge states may occur in a wide class of magnetic systems.

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Wojciech Brzezicki, Mario Cuoco. 2017-01-28. Topological Gapless Phases in Non-Symmorphic Antiferromagnets. https://doi.org/10.1103/physrevb.95.155108

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