Topological Semimetal features in the Multiferroic Hexagonal Manganites

Abstract

Using first-principles calculations we examine the band structures of ferromagnetic hexagonal manganites $\mathrm{YX}{\mathrm{O}}_3$ (X=V, Cr, Mn, Fe and Co) in the nonpolar nonsymmorphic $P{6}_3/mmc$ space group. For $\mathrm{YV}{\mathrm{O}}_3$ and $\mathrm{YCr}{\mathrm{O}}_3$ we find a band inversion near the Fermi energy that generates a nodal ring in the $k_z=0$ mirror plane. We perform a more detailed analysis for these compounds and predict the existence of the topological "drumhead" surface states. Finally, we briefly discuss the low-symmetry polar phases (space group $P{6}_{3}cm$) of these systems, and show they can undergo a $P{6}_3/mmc\to P{6}_{3}cm$ transition by condensation of soft $K_3$ and ${\Gamma }_2^{-}$ phonons. Based on our findings, stabilizing these compounds in the hexagonal phase could offer a promising platform for studying the interplay of topology and multiferroicity, and the coexistence of real-space and reciprocal-space topological protection in the same phase.

References in corpus (6)

• Weyl semimetal phase in non-centrosymmetric transition metal monophosphides
• Phase transition between the quantum spin Hall and insulator phases in 3D: emergence of a topological gapless phase
• Magnetic structure of hexagonal YMnO3 and LuMnO3 from a microscopic point of view
• Structural, electronic, and magneto-optical properties of YVO${}_3$
• Topological Weyl and Node-Line Semimetals in Ferromagnetic Vanadium-Phosphorous-Oxide $\beta$-V${}_2$OPO${}_4$ Compound
• Weyl Ferroelectric Semimetal