Optimising Spintronics: The Strategic Value of Quaternary Heusler Compounds

CoMnCrGa, a specific configuration within the family of quaternary Heusler compounds, has been identified as a stable ferromagnetic candidate for advanced energy harvesting and data storage. First-principles calculations indicate it possesses high thermal stability and tunable conductivity, addressing key limitations in current material science. The material stabilises in a Type-I cubic structure ($F\bar{4}3m$), providing a robust foundation for next-generation devices.

The Stability Deficit in Quaternary Heusler Compounds

Modern electronics face a thermal bottleneck. As devices shrink, heat density increases, degrading performance. Spintronics—electronics that utilise electron spin rather than just charge—requires materials that maintain magnetic order at room temperature. Many candidates fail under thermal stress or lack the necessary polarisation efficiency. The industry demands materials that combine structural robustness with precise electronic control. Without this, the transition from silicon-based logic to spin-based logic remains theoretically sound but practically unfeasible.

Solution: The CoMnCrGa Configuration

The study isolates CoMnCrGa as a solution. It exhibits a ferromagnetic ground state with a total magnetic moment of approximately 1.09 Bohr magnetons ($\mu_B$). This value adheres strictly to the Slater-Pauling rule. This adherence is significant. It suggests the material possesses a nearly half-metallic character. In practice, this means one spin channel acts as a conductor while the other behaves as an insulator, creating a natural filter for electron spin. This nearly half-metallic character is corroborated by high electronic spin polarisation.

Mechanism: Berry Curvature and Transport

The efficiency of CoMnCrGa derives from its internal quantum mechanics. Prominent Berry curvature hotspots exist near the Fermi level. These hotspots act effectively as an internal magnetic field, driving substantial anomalous transport responses without external magnetic influence. The study measured an anomalous Hall conductivity of $\sim -325.7$ S/cm at -158.8 meV. Furthermore, the material demonstrates an anomalous Nernst conductivity (ANC) of $\sim -0.828$ A/m-K at a specific energy shift of -55.6 meV. A large spin Hall conductivity of $\sim 128 (\hbar/e)$ (S/cm) was also identified at 198.8 meV, driven by strong spin-orbit coupling. These metrics indicate that CoMnCrGa can manipulate spin currents with exceptional efficiency.

Impact: Tunability and Application

The primary strategic advantage of CoMnCrGa lies in its tunability. The ANC is not static; it demonstrates exceptional responsiveness to electron doping. By adjusting the chemical potential ($\mu = 0.3$ eV), the ANC reaches $\sim 0.75$ A/m-K at room temperature. This tunability allows engineers to calibrate the material for specific thermal environments. Consequently, CoMnCrGa may serve as a premier material for spin-caloritronic devices, which convert waste heat into usable electric voltage. This capability suggests a pathway toward self-powering logic gates and high-density magnetic memory that operates with minimal energy loss.