ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
ac susceptibility (χ) and magnetoresistance (MR) have been measured in Co-rich amorphous ferromagnets [Fe5Co50Ni17−xCrx(BSi)28 (x=0,5,10,15), Fe5Co50Mn17(BSi)28, and Fe7.8Co31.2Ni24Mn15(BSi)22] to understand the changes in magnetic phase brought by the addition of Cr/Mn. The Tc decreases monotonically with Cr/Mn addition. Samples with x=0–15 remain ferromagnetic down to 16 K. But for the Mn substituted samples below 80 K, χ decreases drastically and at 16 K it is only 5% of its value at 80 K indicating spin freezing. dc magnetization data show a peak around 30 K as well as a time dependence in the Mn17 sample. Presence of significant ferromagnetic anisotropy of resistance (FAR) even at the lowest temperature for both Mn-containing samples indicates that ferromagnetism persists even when transverse spin freezing is present. With lowering of temperature FAR increases, and below 30 K it should have decreased considerably if the lowest temperature phase was purely spin-glass-like but here it remains almost constant. The high-field slopes for T 〈 Tc in both orientations are negative. In particular, for Mn15 sample the slope has a broad maximum decreasing on both sides as T → Tc and T〈80 K. This behavior is interpreted in terms of a transverse spin freezing. We conclude that the lowest temperature (〈30 K) phase in samples containing Mn is a mixture of spin-glass and long-range ferromagnetism. Samples containing Cr show a large positive slope for T 〈 Tc and a very low FAR. The ratio Δρ(parallel)/Δρ⊥ ((approximately-equal-to)0) indicates that the domain magnetization lies in the ribbon plane and is parallel to the ribbon axis.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.349982
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