MAGNETIC-PROPERTIES OF CU80CO20 AND CU80CO15FE5 MELT-SPUN RIBBONS

Citation
M. Rubinstein et al., MAGNETIC-PROPERTIES OF CU80CO20 AND CU80CO15FE5 MELT-SPUN RIBBONS, Physical review. B, Condensed matter, 50(17), 1994, pp. 12550-12558
Citations number
21
Categorie Soggetti
Physics, Condensed Matter
ISSN journal
01631829
Volume
50
Issue
17
Year of publication
1994
Pages
12550 - 12558
Database
ISI
SICI code
0163-1829(1994)50:17<12550:MOCACM>2.0.ZU;2-N
Abstract
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.