IrSi3As3: a first transition metal arsenide non-linear optical material

Abstract

Noncentrosymmetric (NCS) silicon phosphides have recently shown promise as nonlinear optical materials due to the balance of strong second harmonic generation (SHG) activity and large laser damage threshold (LDT) values. While arsenides of electropositive metals, such as Ba, Mg, Zn, and Cd were explored, no NLO properties for transition metal tetrel arsenides have yet been reported. IrSi₃As₃ is a novel compound, isostructural to IrSi₃P₃, which allows a direct investigation on the impact of the heavier pnictogen on structural and optical properties. The direct bandgap is reduced from 1.8 eV for IrSi₃P₃ to 1.55 eV for IrSi₃As₃. Unlike many NLO chalcogenides, IrSi₃As₃ has a small bandgap without compromising the balance between SHG signal and high LDT values. IrSi₃As₃ was found to outperform both its phosphide analogue IrSi₃P₃, as well as the state-of-the-art infrared SHG standard AgGaS₂ (AGS) in SHG activity and the LDT.