Theoretical and Experimental Investigation of CoMoFeAl and Related Compounds

Heusler compounds exhibiting high spin polarization at the Fermi level have attracted much attention with potential application in spintronic devices because of their tunable magnetic and electronic properties, and high Curie temperature much above room temperature. We have carried out joint theoretical and experimental investigations of such three Heusler compounds CoMoFeAl, CoMo_0.5Fe_1.5Al, and Co_1.5Mo_0.5FeAl. Our first-principle calculations show that all three compounds show either ferro- or ferrimagnetic order with CoMoFeAl, CoMo_0.5Fe_1.5Al exhibiting high spin polarization of almost 80%. The investigated samples were prepared using arc melting and high vacuum annealing. All the samples show cubic crystal structures with disorder. The parent compound CoMoFeAl shows ferromagnetic order with moderate saturation magnetization of 11.8 emu/g, and a Curie temperature of 480 K. The other two compounds, namely, Co_1.5Mo_0.5FeAl and CoMo_0.5Fe_1.5Al, show ferrimagnetic order with slightly high saturation magnetizations of 62 emu/g and 54 emu/g, respectively, and substantially higher Curie temperatures close to 1000 K. These results indicate that the investigated compounds may have magnetic and spintronic applications where moderate magnetization and high Curie temperatures are desired.