Design of electrides: from magnetism to topological phases

In our most recent work is featured as an Editor suggestion’s in Phys Rev. Materials!

In this work, we propose a design scheme to explore potential electrides. The searches start with rare-earth-based ternary halides, then we remove the halogen anions and perform global structure optimization to obtain thermodynamically stable or metastable phases with an excess of electrons in confined interstitial cavities. Then, a chemical substitution is performed using magnetic lanthanides.

Nodal line of LaC in the reciprocal space. The left and right panels are viewed from x and y directions, respectively. (e) The Zak phase integrated along the y-direction. Green and white separately stand for π and 0 values. High-symmetry points in this reduced reciprocal space are also shown. (f), (g) Real branches of wave functions

To demonstrate the capability of our approach, we test with 11 ternary halides and successfully predict 30 stable and metastable phases of nonmagnetic electrides subject to three different stoichiometric categories, and successively 28 magnetic electrides via chemical substitution with Gd. 56 out of these 58 designed electrides are discovered for the first time. Two electride systems, the monoclinic AC (A= La, Gd) and the orthorhombic A2Ge (A= Y, Gd), are thoroughly studied to exemplify the set of predicted crystals. Interestingly, both systems turn out to be topological nodal line electrides in the absence of spin-orbit coupling and manifest spin-polarized interstitial states in the case of A= Gd. Our work establishes a novel computational approach of functional electrides design and highlights the magnetism and topological phases embedded in electrides.

Published in April 2021. Link: https://journals.aps.org/prmaterials/abstract/10.1103/PhysRevMaterials.5.044203