Structure inversion asymmetry enhanced electronic structure and electrical transport in 2D A3SnO (A = Ca, Sr, and Ba) anti-perovskite monolayers

Abstract

Anti-perovskites A3SnO (A = Ca, Sr, and Ba) are an important class of materials due to the emergence of Dirac cones and tiny mass gaps in their band structures originating from an intricate interplay of crystal symmetry, spin-orbit coupling, and band overlap. This provides an exciting playground for modulating their electronic properties in the two-dimensional (2D) limit. Herein, we employ first-principles density functional theory (DFT) calculations by combining dispersion-corrected SCAN + rVV10 and mBJ functionals for a comprehensive side-by-side comparison of the structural, thermodynamic, dynamical, mechanical, electronic, and thermoelectric properties of bulk and monolayer (one unit cell thick) A3SnO anti-perovskites. Our results show that 2D monolayers derived from bulk A3SnO anti-perovskites are structurally and energetically stable. Moreover, Rashba-type splitting in the electronic structure of Ca3SnO and Sr3SnO monolayers is observed owing to strong spin-orbit coupling and inversion asymmetry. On the other hand, monolayer Ba3SnO exhibits Dirac cone at the high-symmetry Γ point due to the domination of band overlap. Based on the predicted electronic transport properties, it is shown that inversion asymmetry plays an essential character such that the monolayers Ca3SnO and Sr3SnO outperform thermoelectric performance of their bulk counterparts.

A first-principles prediction of novel Janus T′-RuXY (X/Y = S, Se, Te) monolayers: structural properties and electronic structures

“…[10][11][12][13] The atomic structure of 2D monolayers can exist in many different symmetry forms at the ground state, such as 1T, 2H, and 3R. 14,15 Many 2D materials have a stable structure in the 2H phase (hexagonal structure) and this is also the most investigated structure according to our observations. However, RuS 2 (and also RuSe 2 ) is one of those unusual materials.…”

Effect of vacancy defects on the electronic and mechanical properties of two-dimensional MoSi2N4

“…, LMBJ, 31 TASK, 32 and mTASK 33 meta-GGA functionals) which may have potential applications in the future for a better manifestation of 2D semiconducting and semi-metallic systems. 34,35…”

“…It is to be noted that some new exchangecorrelation potentials proposed in the recent literature (e.g., LMBJ, 31 TASK, 32 and mTASK 33 meta-GGA functionals) which may have potential applications in the future for a better manifestation of 2D semiconducting and semi-metallic systems. 34,35 The top and side views of a monolayer MoSi 2 N 4 , along with its band structure are shown in Fig. 1.…”

Elucidating the Surface Properties of Sr3PbO Inverse‐Perovskite Topological Insulator: A First‐Principles Study

“…On the other hand, introducing inversion asymmetry in these inverse perovskites enhances their experimentally observed thermoelectric properties. [2,13] Among the potential 3D A 3 BO Dirac systems capable of exhibiting topological surface states, Sr 3 PbO (SPO) inverse perovskite crystallizes in the perfect cubic phase with space group # 221 (Pm-3 m) and a lattice parameter of 5.15 Å that does not undergo any structural phase transitions for a wide range of temperatures. [14,15] While the strontium and oxygen ions in SPO adopt their usual þ2 and À2 valence states, respectively, an unusual À4 oxidation state for the Pb atom is in general responsible for giving this material its nontrivial electronic properties.…”

“…Moreover, theoretical studies on bulk systems have also strengthened the prospect of realizing topologically nontrivial electronic structure in thin solid films of A 3 BO inverse perovskites where band inversions might be controlled with layer thickness. [13,18] On the other hand, DFT calculations have also highlighted that sandwiching SPO layers in LaCrO 3 perovskite can be useful for realizing exotic electron behavior such as quantum anomalous Hall effect. [20] Recent experimental studies have shown that the epitaxially grown thin films of SPO on LaAlO 3 substrate exhibit a metallic character with p-type carrier density of around 10 20 cm À3 .…”