Spin gapless semiconductor and nearly spin semimetal antiferromagnets: The case of the inverse Heusler compounds Mn2LiZ (Z = Al and Ga)

Abstract

Using first-principles calculations, we report the structural, electronic, magnetic and electronic transport properties of the new Heusler compounds Mn2LiZ with Z is Al and Ga. We show that both compounds are more stable in the inverse Heusler structure than in the regular one. The band structure calculations indicate that the Mn2LiAl compound is a spin gapless semiconductor and Mn2LiGa is a nearly spin-semimetal. In agreement with the Slater-Pauling rule, the two compounds are non-conventional antiferromagnets: they show zero spin moment accompanied by the fully spin-polarized charge carriers. Strong direct interaction between the spin moments is obtained. Consequently, the mean-field approximation reveals a high Curie temperature in the two compounds. Within the Boltzmann transport theory, the electrical conductivity shows non-metallic behavior for the two compounds at elevated temperatures, and the Seebeck coefficient appears to be large. In particular, the Mn2LiAl compound has a value greater than 150µV/K in a wide temperature range.