Publications

1997

• Experimental Evidence of the Néel-Brown Model of Magnetization Reversal
  
  • Wernsdorfer W.
  • Bonet Orozco E
  • Hasselbach Klaus
  • Benoît A.
  • Barbara B.
  • Demoncy N.
  • Loiseau A.
  • Pascard H.
  • Mailly D.
  Physical Review Letters, American Physical Society, 1997, 78 (9), pp.1791. Presented are the first magnetization measurements of individual ferromagnetic nanoparticles (15–30 nm) at very low temperatures (0.1–6 K). The angular dependence of the hysteresis loop evidenced the single domain character of the particles. Waiting time, switching field, and telegraph noise measurements showed for the first time that the magnetization reversal of a well prepared ferromagnetic nanoparticle can be described by thermal activation over a single-energy barrier as originally proposed by Néel and Brown. The “activation volume” estimated by these measurements was close to the particle volume.
• Spin Reorientation in Substituted Barium Ferrite
  
  • Greneche Jean-Marc
  • Randrianantoandro N.
  • Labaye Y.
  • Boust F.
  • Flavin E.
  • Pascard H.
  Journal de Physique IV Proceedings, EDP Sciences, 1997, 07 (C1), pp.C1-339-C1-340. The structural transformation of substituted hexagonal ferrite powders BaFe10CoTiO19 prepared by mechanical milling, was investigated as a function of grinding time by means of Mössbauer spectrometry and static magnetic measurements. A spin reorientation is clearly evidenced from the temperature dependence of the hyperfine parameters and of the initial magnetic permeability on the powder mechanically treated for 23h. (10.1051/jp4:19971136)
  DOI : 10.1051/jp4:19971136