M. Rubinstein et al., MAGNETIC-PROPERTIES OF CU80CO20 AND CU80CO15FE5 MELT-SPUN RIBBONS, Physical review. B, Condensed matter, 50(17), 1994, pp. 12550-12558
The magnetic properties of granular, annealed, melt-spun ribbons of th
e ''giant'' magnetoresistors, Cu80Co20 and Cu80Co15Fe5, have been stud
ied by a variety of techniques. These include x-ray dfiffraction, elec
tron microscopy, ferromagnetic resonance, SQUID magnetometry, Mossbaue
r-effect spectroscopy, and magnetoresistance. We utilize each of these
measurements to reveal different aspects of the particle size distrib
ution as a function of annealing temperatures. These melt-spun alloys
require large magnetic fields for magnetic saturation, impairing their
utility as magnetic sensors. However, the properties of melt-spun rib
bons provide an understanding of why all granular magnetic materials a
re difficult to saturate. The magnetoresistance ratio of these alloys
is maximized by a 500 degrees C anneal with Delta p/p congruent to 14%
at 4.2 K. The paramagnetic fraction determined by SQUID magnetometry
at 4.2 K is 33% for this annealing temperature. The paramagnetic fract
ion determined by Mossbauer spectroscopy is 14% for samples annealed b
y 500 degrees C, and vanishes when the sample is annealed at 900 degre
es C. The discrepancy between the two measurements of the paramagnetic
fraction is due to the vastly different averaging times of the two te
chniques.