Ferromagnetic-Alloy Phases Near the Compositions Ni2MnIn, Ni2MnGa, Co2MnGa, Pd2MnSb, and PdMnSb

In a search for further examples of Heusler-type alloys, ferromagnetic alloys were found near the composition ${\mathrm{Ni}}_2\mathrm{MnIn}$ , ${\mathrm{Ni}}_2\mathrm{MnGa}$ , ${\mathrm{Co}}_2\mathrm{MnGa}$ , ${\mathrm{Pd}}_2\mathrm{MnSb}$ , and PdMnSb. The first four alloys are tentatively identified as having the $\mathrm{L}{2}_1$ (Heusler)-type structure; PdMnSb, the ${\mathrm{Cl}}_1$ -type structure. Previous work has indicated that ferromagnetism in these types of alloys is associated with Mn-Mn distances in the range 4.17–4.37 A. The present work indicates that ferromagnetism persists with Mn-Mn distances as small as 4.08 A $({\mathrm{Co}}_2\mathrm{MnGa})$ and as large as 4.42 A (PdMnSb); and that ferromagnetism disappears if the Mn-Mn distances become too large. ${\mathrm{Pd}}_2\mathrm{MnSb}$ , with Mn-Mn distance 4.55 A, is only feebly magnetic at room temperature.