Compositiondependent ratio of orbitaltospin magnetic moment in structurally disordered Fe_{x}Pt_{1x} nanoparticles
Abstract
The ratio of orbitaltospin magnetic moment μ^{eff}_{L}/μ^{eff}_{S} averaged over the elementspecific contributions of Fe and Pt has been measured for 3nm Fe_{x}Pt_{1x} nanoparticles at room temperature using the multifrequency electron paramagnetic resonance method for different concentrations of Fe. From a detailed gfactor analysis we determine that the ratio decreases from μ^{eff}_{L}/μ^{eff}_{S}=0.049 for x=0.43 to μ^{eff}_{L}/μ^{eff}_{S}=0.016 for x=0.70 which is much smaller than the bulk iron value (μ^{Fe}_{L}/μ^{Fe}_{S}=0.045). The observed concentration dependence is much stronger than the one calculated for Fe_{x}Pt_{1x} bulk samples and reveals likely changes of the confined electronic structure of the nanoparticle system. The ratio μ^{eff}_{L}/μ^{eff}_{S} takes the lowest value at the concentration (x=0.70) where the magnetic anisotropy energy vanishes in bulk alloys. For x>0.72 a phase transition from a fcc to the Fe bcc structure occurs resulting in the increased bulk ratio again.
 Publication:

Physical Review B
 Pub Date:
 February 2004
 DOI:
 10.1103/PhysRevB.69.054417
 Bibcode:
 2004PhRvB..69e4417U
 Keywords:

 76.50.+g;
 81.07.b;
 Ferromagnetic antiferromagnetic and ferrimagnetic resonances;
 spinwave resonance;
 Nanoscale materials and structures: fabrication and characterization