Title: Survey of the class of isovalent antiperovskite alkaline-earth pnictide compounds

Abstract

The few reported members of the antiperovskite structure class $$Ae_3Pn_APn_B$$ of alkaline earth $(Ae = Ca$,Sr,Ba) pnictides $(Pn = N$,P,As,Sb,Bi) compounds are all based on the $$B$$-site anion $$Pn_B$$ = N. All fit can be categorized as narrow gap semiconductors, making them of interest for several reasons. Because chemical reasoning suggests that more members of this class may be stable, we provide here a density functional theory (DFT) based survey of this entire class of 3 x 5 x 5 compounds. We determine first the relative energetic stability of the distribution of pairs of $Pn$ ions in the $$A$$ and $$B$$ sites of the structure, finding that the $$B$$ site always favors the small pnictogen anion. The trends of the calculated energy gaps with $Ae$ cation and $Pn$ anions are determined, and we study effects of spin-orbit coupling as well as two types of gap corrections to the conventional DFT electronic spectrum. Because there have been suggestions that this class harbors topological insulating phases, we have given this possibility attention and found that energy gap corrections indicate the cubic structures will provide at most a few topological insulators. Structural instability is addressed by calculating phonon dispersion curves for a few compounds, with one outcome being that distorted structures should be investigated further for thermoelectric and topological character. Examples of the interplay between spin-orbit coupling and strain on the topological nature are provided. Finally, a case study of $$Ca_3BiP$$ including the effect of strain illustrates how a topological semimetal can be transformed into topological insulator and Dirac semimetal.

Authors:

Goh, Wen Fong ^[1]; Pickett, Warren E. ^[1]

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+ Show Author Affiliations

1. Univ. of California, Davis, CA (United States). Dept. of Physics

Publication Date:

Thu Jan 04 00:00:00 EST 2018

Research Org.:

Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1544339

Alternate Identifier(s):

OSTI ID: 1415669

Grant/Contract Number:  

AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review B

Additional Journal Information:

Journal Volume: 97; Journal Issue: 3; Journal ID: ISSN 2469-9950

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY