⁵¹V and ⁵⁵Mn Hyperfine Fields in the L2_1-TypeFe_2Mn_1-xV_xSi and Fe_2T_1-xCr_xSi (T=V, Mn) Compounds

Abstract

Hyperfine fields have been measured by the NMR spin-echo technique inzero external field at 4.2 K for intermetallic compoundsFe₂Mn_1-xV_xSi and Fe₂T_1-xCr_xSi (T=V, Mn). Theaverage Fe and Mn magnetic moments are derived using the relationsbetween the hyperfine fields and the atomic magnetic moments in theisomorphic compounds. These moments in Fe₂Mn_1-xV_xSi increasemonotonically with increasing x; for Fe from 0.35μ _B at x=0.2 to0.5μ _B at x=0.75; and for Mn from 2.4μ _B atx=0.2 to 3μ_B at x=0.8. The extrapolation to the V-rich side gives 0.5μ_B/Fe in Fe₂VSi, which is consistent with an extrapolatedsaturation moment of 1.1μ _B/f.u. The results inFe₂T_1-xCr_xSi (T=V, Mn) are also discussed. From thesetogether with saturation moments the transition from a ferromagneticto an antiferromagnetic ordering on the V-rich side inFe₂(Mn, V)Si and Fe₂(V, Cr)Si is suggested.