Computational Investigation of Half-Heusler Compounds for Spintronics Applications (1610.02444v2)

Abstract: We present first-principles density functional calculations of the electronic structure, magnetism, and structural stability of 378 $\textit{XYZ}$ half-Heusler compounds (with $X=$ Cr, Mn, Fe, Co, Ni, Ru, Rh, $Y=$ Ti, V, Cr, Mn, Fe, Ni, $Z=$ Al, Ga, In, Si, Ge, Sn, P, As, Sb). We find that a "Slater-Pauling density of states" with a gap or pseudogap at three states per atom below the gap in at least one spin channel is a common feature in half-Heusler compounds. We find that the presence of such a gap at the Fermi energy in one or both spin channels contributes greatly to the stability of a half-Heusler compound. We calculate the formation energy of each compound and systematically investigate its stability against all other phases in the Open Quantum Materials Database (OQMD). We represent the thermodynamic phase stability of each compound as its distance from the convex hull of stable phases in the respective chemical space and show that the hull distance of a compound is a good measure of the likelihood of its experimental synthesis. We identify 26 18-electron semiconductors, 45 half-metals, and 34 near half-metals with negative formation energy, that follow the Slater-Pauling rule of three electrons per atom. Our calculations predict new thermodynamically stable semiconducting phases NiScAs, RhTiP, and RuVAs, which merit further experimental exploration. Further, two interesting zero-moment half-metals, CrMnAs and MnCrAs, are calculated to have negative formation energy. In addition, our calculations predict a number of new, hitherto unreported, semiconducting (e.g., CoVGe, FeVAs), half-metallic (e.g., RhVSb), near half-metallic (e.g., CoFeSb, CoVP) half-Heusler compounds to lie close to the respective convex hull of stable phases, and thus may be experimentally realized under suitable synthesis conditions, resulting in potential candidates for various spintronics applications.

Computational Investigation of Half-Heusler Compounds for Spintronics Applications

The paper presents an extensive computational paper of 384 half-Heusler compounds using first-principles density functional theory (DFT) calculations to investigate their potential in spintronic applications. Specifically, the authors focus on examining the electronic structures, magnetic properties, and thermodynamic stabilities of these compounds, highlighting the prevalence of Slater-Pauling gaps within their electronic structures.

Half-Heusler compounds are known for their diverse physical properties, ranging from thermoelectricity to topological insulation. A pivotal element of this paper is the identification and characterization of Slater-Pauling gaps—energy gaps or pseudogaps evident in at least one of the spin channels after nine states within the three-atom primitive cell. These gaps are a critical factor in the stability and electronic properties of half-Heusler compounds.

Throughout the paper, the authors use DFT with intricate computational methods, achieving reliable electronic, magnetic, and structural data. Key findings include discovering 45 half-metals and 27 semiconductors with 18 valence electrons per formula unit, which adhere to the Slater-Pauling rule. These results highlight the diversity within the family of half-Heusler compounds and their potential stability when featuring a Slater-Pauling gap.

In terms of stability, the paper explores the calculated formation energies and thermodynamic stabilities of these compounds, gauged by their distance from the convex hull. The hull distance serves as an indicator of a compound's likelihood to be synthesized experimentally, with many compounds determined to be energetically competitive. Particularly, compounds with $X =$ Co, Rh, or Ni, $Y=$ Ti or V, and $Z=$ P, As, Sb, or Si are underscored for their promising stability indicators.

Of notable interest are the zero-moment half-metals, such as CrMnAs and MnCrAs, which offer unique magneto-electronic properties due to their zero net magnetic moments while maintaining half-metallic behavior. These findings propose intriguing possibilities for spintronic devices, emphasizing the potential for rapid developments in AI and computational material design.

The paper posits several half-Heusler compounds as candidates for experimental exploration, especially those projected to be thermodynamically stable or near-stable. These include semiconducting phases such as RuVAs, new half-metallic predictions, and other near half-metallic systems. The comprehensive analysis within this research furthers the understanding of half-Heusler compounds and sets the stage for future studies aimed at harnessing these materials for advanced technological applications.

In conclusion, this paper provides insightful advancements into the electronic and magnetic properties of half-Heusler compounds, showcasing their significant prospective use in spintronics. The implications of these findings, including the stability and novel properties of the identified systems, suggest a fertile ground for experimental verifications and technological innovations. As techniques in AI continue to evolve, studies such as this one can benefit from enhanced computational modeling, possibly elucidating even more complex material behaviors and widening the scope of material applications in electronics.