Average Magnetization and Fe Hyperfine Fields in Co2FeSi-based Heusler Alloys

L.F. Kiss, G. Bortel, L. Bujdosó, D. Kaptás, T. Kemény, and I. Vincze Wigner Research Centre for Physics, Hungarian Academy of Sciences, H-1525 Budapest, P.O.Box 49, Hungary

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In the present study SQUID magnetic and 57Fe Mössbauer measurements were performed on bulk Co2FeAl1-xSix, Co2Fe0.9TM0.1Si (TM = Ti, V, Cr, Mn, Co, Ni, Cu), Co2-yFe1+ySi and Co2Fe1+zSi1-z samples prepared by induction melting. The Co2FeAl1-xSix shows the L21 crystal structure only for x ≥ 0.5, between x = 0 and 0.3 it has the B2 structure (Fe-Al, Si disorder). The average magnetization of these alloys does not follow the expected Slater-Pauling trend (on the Si side saturation is observed around 5.75 μB/f.u.) and similar deviation is observed for the replacement of Fe by transition metal (TM) atom. The effect of the antisite disorder (Fe-Si) on the magnetization and Fe hyperfine parameters was determined and significant decrease in the Co magnetic moment for excess Si neighbourhood is extrapolated. The formerly reported large ≈ 6 μB/f.u. magnetization for Co2FeSi was observed only in samples having Fe excess and Si deficiency.

DOI: 10.12693/APhysPolA.127.347 PACS numbers: 75.50.Cc, 76.80.+y