Title :
Influence of the doping on the time-dependent magnetic behaviour of fine particles
Author :
Bottoni, Giancarlo ; Candolfo, Donato ; Cecchetti, Antonio
Author_Institution :
Dipartimento di Fisica, Ferrara Univ., Italy
fDate :
11/1/1994 12:00:00 AM
Abstract :
Time dependent magnetic phenomena are analysed by measuring the changes of magnetization with time in the presence of a constant field on fine particles containing various percentage of dopants. The samples analysed are: iron oxides (Co-doped), CrO2 (Fe/Sb- and Ir-doped) and Ba ferrite (Co/Ti-doped) particles. The doping causes a large increase of the coefficient S which characterizes the magnetic viscosity, and an increase of the thermal fluctuation field Hf. The “activation volume” Vac, which is considered as the region of greatest magnetic instability in the particle and the “switching volume” Vc decrease with doping. These effects are principally attributed to the increase of the anisotropy directions distribution inside the particles and to the evolution of the magnetization reversal mode in the modified particles
Keywords :
magnetic aftereffect; magnetic anisotropy; magnetic particles; magnetic switching; magnetisation reversal; BaFe12O19:Co,Ti; Co-doped iron oxides; Co/Ti-doped Ba ferrite; CrO2:Fe,Sb; CrO2:Ir; Fe/Sb-doped CrO2; Fe2O3:Co; Ir-doped CrO2; activation volume; anisotropy; doping; fine particles; magnetic instability; magnetic viscosity; magnetization; magnetization reversal; switching volume; thermal fluctuation field; time-dependent magnetic behaviour; Doping; Ferrites; Iron; Magnetic analysis; Magnetic anisotropy; Magnetic field measurement; Magnetization; Particle measurements; Perpendicular magnetic anisotropy; Time measurement;
Journal_Title :
Magnetics, IEEE Transactions on
