Co nanoparticles inserted into a porous carbon amorphous matrix: the role of cooling field and temperature on the exchange bias effect.
We report unusual cooling field dependence of the exchange bias in oxide-coated cobalt nanoparticles embedded within the nanopores of a carbon matrix. The size-distribution of the nanoparticles and the exchange bias coupling observed up to about 200 K between the Co-oxide shell (∼3-4 nm) and the ferromagnetic Co-cores (∼4-6 nm) are the key to understand the magnetic properties of this system. The estimated values of the effective anisotropy constant and saturation magnetization obtained from the fit of the zero-field cooling and field cooling magnetization vs. temperature curves agree quite well with those of the bulk fcc-Co.
Dpto. De Física, Universidad de Oviedo, c/Calvo Sotelo s/n 33007, Oviedo, Spain. fernandezpaz.uo@uniovi.es
María Paz
MP
Fernández-García
Pedro
P
Gorria
Marta
M
Sevilla
Antonio B
AB
Fuertes
Roberto
R
Boada
Jesús
J
Chaboy
Giuliana
G
Aquilanti
Jesús A
JA
Blanco
D002244:Carbon / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry*; D008280:Magnetics; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D010087:Oxides / Q000737:chemistry*; D016062:Porosity; D013696:Temperature
D010087:Oxides; D003035:Cobalt; D002244:Carbon; C060728:cobalt oxide