Spin gapless semiconductor and nearly spin semimetal antiferromagnets: The case of the inverse Heusler compounds Mn2LiZ (Z = Al and Ga). (November 2021) - Hadji, Tariq
Highlights: The Mn2 LiZ (Z = Al and Ga) Heusler alloys have been investigated. The Mn2 LiAl is a spin gapless semiconductor and Mn2 LiGa is a nearly spin-semimetal. A strong direct interaction of the spin moments are obtained. A high Curie temperature T C was obtained for all the studied compounds. A non-metallic behavior for the two compounds at elevated temperatures was obtained using the Boltzmann transport theory. Abstract: Using first-principles calculations, we report the structural, electronic, magnetic and electronic transport properties of the new Heusler compounds Mn2 LiZ 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 Mn2 LiAl compound is a spin gapless semiconductor and Mn2 LiGa 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 Mn2 LiAl compound has a value greater than 150µV/K in a wide temperature range. Graphical abstract: Image, graphical abstract