The paper investigates the half-metallic behavior and Slater-Pauling behavior of full-Heusler alloys based on Co, Fe, Rh, and Ru. Using the full-potential screened Korringa-Kohn-Rostoker (FSKKR) method, the authors find that these alloys exhibit half-metallic behavior, with a very small energy gap in the minority band due to localized states at the Co (Fe, Rh, or Ru) sites. The total spin-magnetic moment per unit cell ($M_t$) scales with the total number of valence electrons ($Z_t$) following the rule: $M_t = Z_t - 24$. The authors explain why the spin-down band contains exactly 12 electrons using group theory arguments and show that this rule holds for compounds with less than 24 valence electrons. They also discuss deviations from this rule and differences compared to half-Heusler alloys. The study highlights the unique properties of full-Heusler alloys, which can be engineered to have diverse magnetic properties.The paper investigates the half-metallic behavior and Slater-Pauling behavior of full-Heusler alloys based on Co, Fe, Rh, and Ru. Using the full-potential screened Korringa-Kohn-Rostoker (FSKKR) method, the authors find that these alloys exhibit half-metallic behavior, with a very small energy gap in the minority band due to localized states at the Co (Fe, Rh, or Ru) sites. The total spin-magnetic moment per unit cell ($M_t$) scales with the total number of valence electrons ($Z_t$) following the rule: $M_t = Z_t - 24$. The authors explain why the spin-down band contains exactly 12 electrons using group theory arguments and show that this rule holds for compounds with less than 24 valence electrons. They also discuss deviations from this rule and differences compared to half-Heusler alloys. The study highlights the unique properties of full-Heusler alloys, which can be engineered to have diverse magnetic properties.