This paper aims to perform a systematic density functional study on alkali-metal-based half-Heusler compounds, namely $A\mathrm{Cr}Z$ ($A=\mathrm{Li}$, Na, and K; $Z=\mathrm{As}$, Sb, and P), to identify the optimal half-metal (HM) for practical applications. Unlike most HMs proposed so far, the majority of ACrZ compounds in our study exhibit a wide band gap (1.60–2.38 eV) and retain robust half-metallicity even at the surface. Furthermore, the half-metallicity is robust under severe strain, up to 10%. Because of their stability, robust half-metallicity at the surface and under strain, and good lattice mismatch with zinc-blende semiconductors, we propose $\mathrm{LiCr}Z$ and $\mathrm{NaCr}Z$ ($Z=\mathrm{As}$ and Sb) as promising compounds for practical applications to spintronics.

• Received 11 January 2022
• Revised 25 March 2022
• Accepted 19 April 2022

DOI:https://doi.org/10.1103/PhysRevMaterials.6.055001