High Curie temperature and possible canted magnetism in free Gd clusters

The magnetic properties of free Gd-N clusters (N = 13, 21, and 22) have bee n measured between 90 and 600 K in a Stern-Gerlach experiment. Gd-13 and Gd -21 are found to be superparamagnetic (SP) whereas Gd-22 is not. Within the SP model, the magnetic moment per atom at 100 K is 5.4 mu(B) for Gd-13 and 5 mu(B) for Gd-21, lower than the bulk value, 7.55 mu(B). We measure Curie temperatures of 420 +/- 20 K for Gd-21 and over 500 K for Gd-13, significa ntly higher than 293 K, the bulk value. A canted magnetic moment model is c ompatible with the experimental data.