Magic numbers in the magnetic properties of gadolinium clusters

Abstract

Gadolinium clusters (N=11--92) in a molecular beam exhibit dramatic size dependences in their magnetic properties. Two principal behaviors are observed: rigid rotor precession and nutation when the magnetic moment is tightly locked to the lattice by crystal anisotropy, and superparamagnetism when the moment is approximately free. Partially locked behavior is also seen. Magnetic moments of about 3${\mathrm{\ensuremath{\mu}}}_{\mathit{B}}$ per atom are observed, with Curie temperatures substantially above the bulk value. Moments that remain locked above 300 K may permit ultrahigh-density magnetic memory.