Atomic Scale Characterization and Magneto-Transport Properties of Mechanically Milled Cu–Co Type Alloys

Abstract

We have prepared Cu 80 Co 20 powders by high-energy ball milling under ambient atmosphere. The evolutions of both the microstructure and the magnetic properties have been investigated as a function of milling time. 3D-focused ion beam was used for microstructural characterization for low milling time (1.5 h). For higher milling time (20 h) atom probe tomography was used to investigate at the atomic scale the elemental distribution of chemical species. In the first steps of milling, the powder presents a ferromagnetic signal due to the presence of micrometric cobalt particles. After 20 h of milling, the powder is composed of CoO particles with diameter around 10−50 nm surrounded by a copper rich matrix (Cu-84 ± 2%, Co-16 ± 2%) and a few cobalt-rich nanoclusters. For this milling time, a typical giant magnetoresistive effect is observed. A positive magnetoresistive effect is also observed at 5 K under low magnetic fields, which is related to the presence of Co oxides clusters. After a heat treatment at 450°C for 1 h, the precipitation of Co into the copper rich matrix is observed, the giant magnetoresistive effect is enhanced, and the positive magnetoresistive effect disappears.

Electrodiffusion versus Chemical Diffusion in Alkali Calcium Phosphate Glasses: Implication of Structural Changes

“…The question often remains of how reversible are these changes . Helpful techniques for elucidating the role of dynamical changes of structures include solid-state NMR ,, but also FIB-TEM and atom probe tomography. , …”

“…51 Helpful techniques for elucidating the role of dynamical changes of structures include solid-state NMR 42,52,53 but also FIB-TEM 20 and atom probe tomography. 54,55 4. SUMMARY AND OUTLOOK A long-term bombardment of a sodium-containing calcium phosphate glass with a potassium ion beam has been carried for a time span of 120 h. The electrodiffusion induced by this bombardment has been quantitatively analyzed by means of ToF-SIMS.…”

CONFIGURATION OF Co PHASE AND MAGNETORESISTANCE PROPERTIES IN HIGH ENERGYMILLED Co-CGRANULAR COMPOUNDS

“…Penelitian dan pengembangan paduan bahan berbasis granular Kobalt (Co) seperti Co-Al [1], Co-Cu [2] telah banyak dilakukan, termasuk Co-C 60 [3]. Hal ini karena sistem paduan tersebut memiliki sifat Giant Magnetoresistance (GMR).…”