A neutron depolarization study of low temperature magnetic hardening in Fe-Nb-Cr-B-Cu nanocrystalline alloys

The magnetic properties of nanocrystalline Fe73,5Nb4.5Cr5B16Cu1 alloy have been studied by neutron depolarization (ND) and magnetization measurements in a temperature range between 2 and 300 K. The obtained data have confirmed the strong magnetic hardening at low temperatures characterized by rapid increase of coercive field by nearly two orders of magnitude below similar to30 K. We show that this hardening goes along with the significant irreversibility between field-cooling (FC) and zero-field cooling magnetization at low fields. The three-dimensional neutron depolarization analysis allowed us to characterize simultaneously the macroscopic magnetization, the magnetic domain size and texture. It is shown that a significant role in the magnetic behavior at low temperatures is played by the presence of spin freezing effects. (C) 2003 Elsevier B.V. All rights reserved.