Magnetization enhancement at low temperature due to surface ordering in Fe-Ni-B amorphous nanoparticles

DE BIASI EMILIO; ZYSLER ROBERTO; RAMOS CARLOS; ROMERO HÉCTOR

PHYSICA B - CONDENSED MATTER

Año: 2002 vol. 320 p. 203 - 205

0921-4526

We report magnetization measurements up to 5T as a function of temperature from 5 to 300K in an amorphous Fe– Ni–B system nanoparticle (average diameter B3 nm). These nanoparticles were dispersed in a non-magnetic polymer matrix to minimize interparticle interactions and the results were contrasted with a concentrated powder sample. The saturation magnetization shows a sudden increase below 40 K. This behavior is observed in both the dispersed and the concentrated systems, being noticeably more pronounced in the first. This result can be explained considering that the large magnetic contribution at low T is due to the magnetic ordering of the particle surface.B3 nm). These nanoparticles were dispersed in a non-magnetic polymer matrix to minimize interparticle interactions and the results were contrasted with a concentrated powder sample. The saturation magnetization shows a sudden increase below 40 K. This behavior is observed in both the dispersed and the concentrated systems, being noticeably more pronounced in the first. This result can be explained considering that the large magnetic contribution at low T is due to the magnetic ordering of the particle surface.T is due to the magnetic ordering of the particle surface.