Publications

1996

• Dynamical measurement of domain-wall nucleation and annihilation in individual amorphous Co particles
  
  • Wernsdorfer W.
  • Hasselbach Klaus
  • Sulpice A.
  • Wegrowe J.-E
  • Thomas L.
  • Barbara B.
  • Mailly D.
  Physical Review B: Condensed Matter and Materials Physics (1998-2015), American Physical Society, 1996, 53 (6), pp.3341. We present magnetization measurements of individual amorphous Co particles 300 nm200 nm30 nm patterned by electron-beam lithography. The hysteresis loops show mainly two magnetization jumps corresponding to domain-wall nucleation and annihilation. The angular dependence of these magnetization jumps is measured and the temperature dependence 0.1– 6 K of the nucleation and the annihilation processes is investigated by two independent methods: switching field and switching time measurements. Finally we compare the results obtained on one particle with those of an array of about 210 7 particles. We show experimentally that the dynamical properties measured on individual particles are connected with an unusual 1/T relaxation of the array of particles.
• Spectroscopic evidence for large (>>1 µm) lithium-colloid creation in electron-irradiated Li2O single crystals
  
  • Beuneu Francois
  • Vajda Peter
  Physical Review Letters, American Physical Society, 1996, 76, pp.4544. We have created lithium metal colloids by electron-irradiating single crystals of lithium oxide near 0°C. The striking feature is the observation of two kinds of colloids manifesting themselves as two EPR metallic lines, the narrow line corresponding to small metallic clusters (size < 1 µm) and the broad one associated with large metallic colloids visible by optical microscopy (~ 20 µm). The latter are also observed by NMR. A further indication for the presence of colloids of different types is the differing recovery behavior of the two EPR lines in an annealing treatment.