6533b827fe1ef96bd1286e10

RESEARCH PRODUCT

Stabilizing and increasing the magnetic moment of half-metals: The role of Li in half-HeuslerLiMnZ(Z=N,P,Si)

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Due to their similarities to metastable zinc-blende half-metals, we systematically examined the half-Heusler compounds $\ensuremath{\beta}\text{-LiMn}Z$ ($Z=\text{N},\text{P}$ and Si) for their electronic, magnetic, and stability properties at optimized lattice constants and strained lattice constants that exhibit half-metallic properties. We also report the other phases of the half-Heusler structure ($\ensuremath{\alpha}$ and $\ensuremath{\gamma}$ phases), but they are unlikely to be grown. The magnetic moments of these stable Li-based compounds are expected to reach as high as $4{\ensuremath{\mu}}_{\mathrm{B}}$ per unit cell when $Z=\text{Si}$ and $5{\ensuremath{\mu}}_{\mathrm{B}}$ per unit cell when $Z=\text{N}$ and P; however, the antiferromagnetic spin configuration is energetically favored when $Z$ is a pnictogen. $\ensuremath{\beta}$-LiMnSi at a lattice constant 14% larger than its equilibrium lattice constant is a promising half-metal due to its large magnetic moment, large gap, and vibrational stability. The modified Slater-Pauling rule for these compounds is determined. Finally, we investigated a plausible method for developing half-metallic $\mathrm{Li}{}_{x}\mathrm{Mn}Z$ at equilibrium by tuning $x$, but this type of alloying introduces local structural changes that preclude half-metallicity.