Evidence of large surface effects in Co-Ni-B amorphous nanoparticles

ZYSLER ROBERTO; ROMERO HÉCTOR; RAMOS CARLOS; DE BIASI EMILIO; FIORANI DINO

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

Año: 2003 vol. 266 p. 233 - 242

0304-8853

The results of magnetization measurements on B3 nm amorphous (Co0.25Ni0.75)65B35 nanoparticles, in a diluted dispersion (4% in a polymer) and in a powder form, are reported. The results of MðTÞ and MðHÞ measurements give evidence of an important surface contribution to magnetization, which is responsible for a non-saturated component in the magnetization curves and for some anomalies in the coercive field and temperature dependence of the remanence for the sample of dispersed particles, where interparticle interactions can be neglected. The results have been interpreted witha simple model where eachsingle-domain nanoparticle is considered as a core–shell system, withuniaxial anisotropy on the core and surface anisotropy on the shell. anisotropy on the core and surface anisotropy on the shell. evidence of an important surface contribution to magnetization, which is responsible for a non-saturated component in the magnetization curves and for some anomalies in the coercive field and temperature dependence of the remanence for the sample of dispersed particles, where interparticle interactions can be neglected. The results have been interpreted witha simple model where eachsingle-domain nanoparticle is considered as a core–shell system, withuniaxial anisotropy on the core and surface anisotropy on the shell. anisotropy on the core and surface anisotropy on the shell. dispersion (4% in a polymer) and in a powder form, are reported. The results of MðTÞ and MðHÞ measurements give evidence of an important surface contribution to magnetization, which is responsible for a non-saturated component in the magnetization curves and for some anomalies in the coercive field and temperature dependence of the remanence for the sample of dispersed particles, where interparticle interactions can be neglected. The results have been interpreted witha simple model where eachsingle-domain nanoparticle is considered as a core–shell system, withuniaxial anisotropy on the core and surface anisotropy on the shell. anisotropy on the core and surface anisotropy on the shell. evidence of an important surface contribution to magnetization, which is responsible for a non-saturated component in the magnetization curves and for some anomalies in the coercive field and temperature dependence of the remanence for the sample of dispersed particles, where interparticle interactions can be neglected. The results have been interpreted witha simple model where eachsingle-domain nanoparticle is considered as a core–shell system, withuniaxial anisotropy on the core and surface anisotropy on the shell. anisotropy on the core and surface anisotropy on the shell. B3 nm amorphous (Co0.25Ni0.75)65B35 nanoparticles, in a diluted dispersion (4% in a polymer) and in a powder form, are reported. The results of MðTÞ and MðHÞ measurements give evidence of an important surface contribution to magnetization, which is responsible for a non-saturated component in the magnetization curves and for some anomalies in the coercive field and temperature dependence of the remanence for the sample of dispersed particles, where interparticle interactions can be neglected. The results have been interpreted witha simple model where eachsingle-domain nanoparticle is considered as a core–shell system, withuniaxial anisotropy on the core and surface anisotropy on the shell. anisotropy on the core and surface anisotropy on the shell. evidence of an important surface contribution to magnetization, which is responsible for a non-saturated component in the magnetization curves and for some anomalies in the coercive field and temperature dependence of the remanence for the sample of dispersed particles, where interparticle interactions can be neglected. The results have been interpreted witha simple model where eachsingle-domain nanoparticle is considered as a core–shell system, withuniaxial anisotropy on the core and surface anisotropy on the shell. anisotropy on the core and surface anisotropy on the shell. MðTÞ and MðHÞ measurements give evidence of an important surface contribution to magnetization, which is responsible for a non-saturated component in the magnetization curves and for some anomalies in the coercive field and temperature dependence of the remanence for the sample of dispersed particles, where interparticle interactions can be neglected. The results have been interpreted witha simple model where eachsingle-domain nanoparticle is considered as a core–shell system, withuniaxial anisotropy on the core and surface anisotropy on the shell. anisotropy on the core and surface anisotropy on the shell. core–shell system, withuniaxial anisotropy on the core and surface anisotropy on the shell.