Cubic versus spherical magnetic nanoparticles: the role of surface anisotropy.
The magnetic properties of maghemite (gamma-Fe2O3) cubic and spherical nanoparticles of similar sizes have been experimentally and theoretically studied. The blocking temperature, T(B), of the nanoparticles depends on their shape, with the spherical ones exhibiting larger T(B). Other low temperature properties such as saturation magnetization, coercivity, loop shift or spin canting are rather similar. The experimental effective anisotropy and the Monte Carlo simulations indicate that the different random surface anisotropy of the two morphologies combined with the low magnetocrystalline anisotropy of gamma-Fe2O3 is the origin of these effects.
Salazar-Alvarez
G
G
Institut Català de Nanotecnologia, Edifici CM7, Campus Universitat Autònoma de Barcelona, E-08193 Bellaterra (Barcelona), Spain.
Qin
J
J
Sepelák
V
V
Bergmann
I
I
Vasilakaki
M
M
Trohidou
K N
KN
Ardisson
J D
JD
Macedo
W A A
WA
Mikhaylova
M
M
Muhammed
M
M
Baró
M D
MD
Nogués
J
J
D016880:Anisotropy; D007501:Iron / Q000737:chemistry; D008280:Magnetics; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D013499:Surface Properties; D013696:Temperature
D007501:Iron