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

Abstract

The few reported members of the antiperovskite structure class Ae3P nAP nB of alkaline earth (Ae = Ca,Sr,Ba) pnictides (P n = N,P,As,Sb,Bi) compounds are all based on the B-site anion P nB=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 × 5 × 5 compounds. We determine first the relative energetic stability of the distribution of pairs of P n 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 P n 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. A case study of Ca3BiP including the effect of strain illustrates how a topological semimetal can be transformed into topological insulator and Dirac semimetal.

Spin-polarized electronic states and atomic reconstructions at antiperovskite Sr3SnO(001) polar surfaces

“…it is now considered that studying antiperovskites could enable to enlarge again more the range of applications [5,6] and of material candidates to display fundamental quantum properties, such as superconductivity [7] or topological electronic structures [8][9][10]. Understanding, functionalizing and optimizing these properties in a new class of materials requires extensive efforts to characterize their heterostructures and to develop an engineering of defects, surfaces and interfaces [11].…”

Coemergence of Dirac and multi-Weyl topological excitations in pnictide antiperovskites

“…About a dozen compounds have nonzero Z 2 invariants in the assumed cubic structure. 21 The surface spectrum was obtained by first obtaining the maximally-localized Wannier functions and corresponding hopping amplitudes. 26,27 A semi-infinite system is then constructed and the surface spectrum is calculated using the iterative surface Green's function method 28,29 with a tight binding hopping cut-off of 4 unit cells.…”

“…The antiperovskite (APv) structure class of alkaline earth and pnictides compounds has been proposed to harbor potential topological insulating phases. 20,21 Our density functional theory based survey of the entire class of 3 × 5 × 5 possible alkaline earth-pnictide APv compounds, 21 viz. Ae 3 P n A P n B , where Ae = Ca, Sr, Ba and P n A , P n B = N, P, As, Sb, Bi, confirmed that some of these compounds in the assumed cubic structure host, or are very close to, non-trivial topological phases.…”

Epitaxial antiperovskite/perovskite heterostructures for materials design

“…221) but with anion and cation positions interchanged in the unit cell (7). Like their oxide perovskite counterparts, antiperovskite materials show a variety of tunable physical properties, including superconductivity, itinerant antiferromagnetism, giant magnetoresistance, large magnetovolume effects, and topological electronic behavior (8)(9)(10)(11)(12)(13)(14)(15). Among anti perovskite materials, transition metal (TM)-based nitride compounds (M 3 XN; M: TM; X: metallic or semiconducting element) are particu larly interesting as their physical behaviors are remarkably sensitive to external perturbations such as magnetic fields, temperature, or pres sure (14)(15)(16)(17)(18)(19)(20).…”