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Magnetismus Poster: Do., 13:00–15:30 D-P247
Influence of Nd-nanoparticles on hard magnetic properties of bulk amorphous
alloys studied by small-angle neutrons scattering.
Olivier Perroud 1 , Albrecht Wiedenmann 1 , Golden Kumar 2 , Jürgen Eckert 3
1 Hahn-Meitner-Institut Berlin, Glienickerstr. 100, D-14109 Berlin, Germany – 2 NIMS,
1-2-1 Sengen, Tsukuba 305-0047, Japan – 3 TU Darmstadt, Petersenstr. 23, D-64287
Darmstadt, Germany
Bulk amorphous Nd60FexCo30−xAl10-alloys presents hard-magnetic properties for x>5.
Some macroscopic investigations are reported [1], where two Curie temperatures (Tc1 ∼
50 K and Tc2 ∼ 525 K) are observed. This samples exhibits a Fe-rich phase in micrometer
scale, an amorphous matrix and some nanoparticles. The high coercivity were
attributed to the pinning of magnetic domains with some Nd-nanoparticles in the Ferich
phase. Small-angle neutron scattering with polarized neutrons (SANSPOL) allows
to investigate and separate both nuclear and magnetic properties of a sample in the
nanometer scale.
An applied magnetic field of µ0H=6 T doesnt saturated the sample and it follows, that
the magnetic scattering contribution is weak compared to the nuclear one. Previous
SANS experiments and high field measurement on Nd60Fe20Co10Al10-alloy have shown
that the sample was not saturated [2,3] and confirm the presence of magnetic domains.
The present measurements have been performed on the Nd60Fe7.5Co22.5Al10-alloy at
temperatures between 5 K and 550 K and magnetic fields of µ0H=1 T and 6 T. The
scattering curves corroborate the presence of magnetic domains. The Nd-nanoparticles,
which are paramagnetic above Tc1, will act as pinning centers for the domains walls.
This work is supported by the German Science Foundation (DFG) WI 1151/3-1.
[1] G. Kumar et al., J. of Alloys and Compounds 248 309 (2003)
[2] E. Garcia-Matres et al., Physica. B 350 e315-e318 (2004)
[3] O. Perroud et al., Material Science and Engineering A, in press (2006)