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arXiv · 1902.10085

Topological Semimetal features in the Multiferroic Hexagonal Manganites

Sophie F. Weber·Sinéad M. Griffin·Jeffrey B. Neaton
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Abstract

Using first-principles calculations we examine the band structures of ferromagnetic hexagonal manganites $\mathrm{YXO_3}$ (X=V, Cr, Mn, Fe and Co) in the nonpolar nonsymmorphic $P6_3/mmc$ space group. For $\mathrm{YVO_3}$ and $\mathrm{YCrO_3}$ 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 $P6_3cm$) of these systems, and show they can undergo a $P6_3/mmc \rightarrow P6_3cm$ 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.

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Sophie F. Weber, Sinéad M. Griffin, Jeffrey B. Neaton. 2019-02-26. Topological Semimetal features in the Multiferroic Hexagonal Manganites. https://doi.org/10.1103/physrevmaterials.3.064206

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