Structural, Electronic, Magnetic, Mechanical and Optical Properties of RhYZ(Y=Zr,Ir, Nb;Z = Li, As, Sb, Si) Half-Heusler Compounds for Possible Spintronics and Optoelectronics Applications: First-Principles Calculations

Abstract

Half-Heusler (HH) compounds have attracted considerable interest for various advanced tech nological applications owing to their adjustable properties. The ability to fine-tune their prop erties through compositional variation makes them ideal candidates for use in spintronic and optoelectronic devices. The aim of this work was to investigate the structural, mechanical, electronic, optical and magnetic properties of RhYZ (Y = Zr, Ir, Nb; Z = Li, As, Si, Sb) HH compounds by using first-principles calculations based on density functional theory (DFT) as implemented in the QUANTUM ESPRESSO (QE) package. For electronic and magnetic prop erties, both the Generalized Gradient Approximation (GGA) and GGA+U (U is the Hubbard potential) were employed. Structurally, most compounds are stable in type I atomic configura tion, except RhIrZ (Z = As, Si, Sb), which prefer type II. Negative formation energies in their stable configurations indicate thermodynamic stability for most compounds, while RhIrLi shows positive formation energy, suggesting thermodynamic instability. Phonon dispersion calcula tions confirm dynamical stability for all compounds through the presence of positive phonon frequencies across the Brillouin zone. Mechanical stability is also confirmed by satisfying Born and Huang stability criteria. Electronic property analysis shows that RhZrZ (Z = As, Sb) and RhNbSi are semiconductors, making them promising for optoelectronic applications. RhNbZ (Z = As, Sb) compounds are half-metallic, indicating potential for spintronic devices. All other HHcompounds remain metallic under both methods. Partial density of states (PDOS) reveals that transition metal atoms (Rh, Zr, Nb, Ir) dominate the electronic states, while contributions from Li, As, Si, and Sb are less significant. The semiconductor compounds exhibit favorable optical properties, including high real dielectric constant (ε1), strong absorption coefficient (α) and low energy loss (L) in the low photon energy range, further supporting their suitability for optoelectronic devices. Half-metallic compounds also show promising optical features for spin-light interaction applications. In contrast, metallic HH compounds show negative ε1 in the low energy range, making them less ideal for traditional optoelectronics but potentially suit able for plasmonic applications. Magnetic analysis under GGA shows most compounds are non-magnetic, except RhNbSb and RhIrZ (Z = As, Si, Sb). The inclusion of U enhances mag netic response in several systems, particularly RhNbZ (Z = Li, As) and RhIr-based compounds. Comparison with the Slater-Pauling (SP) rule reveals agreement in half-metallic systems, while deviations appear in others.