Magnetic properties of free cobalt and gadolinium clusters

• Published in: Physical review. B, Condensed matter Condensed matter, 1993-05, Vol.47 (19), p.12874-12889
• Main Authors: DOUGLASS, D. C, COX, A. J, BUCHER, J. P, BLOOMFIELD, L. A
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Magnetic properties and materials; Magnetically ordered materials: other intrinsic properties; Metals. Metallurgy; Physics; Saturation moments and magnetic susceptibilities
• ISSN: 0163-1829; 1095-3795
• DOI: 10.1103/physrevb.47.12874

Stern-Gerlach-type magnetic deflection experiments were performed on clusters of cobalt and gadolinium. Cobalt clusters exhibited superparamagnetic behavior over a broad range of temperature, applied magnetic fields, and cluster sizes. An internal magnetic moment per atom of 2.24plus/minus0.14 mu sub B /atom was observed for cobalt clusters containing 65 to 215 atoms at vibrational temperatures between 85 and 300K. The value of magnetic moment was substantially in excess of the bulk value for cobalt. Over a similar temperature range, some gadolinium clusters exhibited superparamagnetic behavior. Others exhibited behavior consistent with their moments being locked to their cluster lattices. In both cases, the internal magnetic moments per atom of gadolinium clusters were considerably reduced from the bulk value for gadolinium. Magnetic behaviors of many gadolinium clusters changed qualitatively as their vibrational temperatures increased. The current controversy concerning experimental cluster vibrational temperatures is also addressed.