https://doi.org/10.1140/epjb/e2003-00250-0
Dynamic susceptibility of reentrant Fe-rich inhomogeneous amorphous alloys
1
Departamento CITIMAC, F. Ciencias, Universidad de Cantabria,
Santander 39005, Spain
2
Departamento de Física, Universidad de Oviedo, Oviedo 33007,
Spain
3
Dept. Elec. y Electrónica, F. Ciencias, Universidad del País Vasco,
Bilbao 48080, Spain
Corresponding author: a barquinl@unican.es
Received:
11
March
2003
Revised:
13
May
2003
Published online:
22
September
2003
Melt-spun amorphous alloys of Fe91Zr9, Fe91Zr7B2, Fe90Zr7B3 and Fe88Zr8B4 have been
characterized by AC susceptibility at frequencies between 30 Hz and 10 KHz. The
measurements reflect the existence of reentrant spin glass transitions below 40 K for all
cases. The transition shift per frequency decade is large compared to the observed in
conventional spin-glass alloys. The shift value increases with the boron content and becomes
closer to values in fine-particle systems. We find that the relaxation in Fe91Zr9 follows a
critical slowing down at the reentrant transition, with exponents and
. The
non-linear susceptibility displays a peak at the transition in this alloy, but wider than in
canonical spin glasses. A Vogel-Fulcher (VF) activation process can explain the frequency
variation in all the Fe-Zr-B alloys. The reduction of the ideal glass temperature in the VF
approach, found in the higher Boron content alloys, is an indication of a superparamagnetic-like behavior. The behavior shown by these alloys is intermediate between a collective
freezing and superparamagnetic-like relaxation. We propose that this is arising due to a
heterogeneous spin structure. The inclusion of a reduced amount of B, affects the magnetic
spin structure.
PACS: 75.50.Lk – Spin glasses and other random magnets / 75.50.Kj – Amorphous and quasicrystalline magnetic materials / 75.40.Gb – Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.)
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2003