Metastability of Free Cobalt and Iron Clusters: A Possible Precursor to Bulk Ferromagnetism

Authors

Xiaoshan Xu, University of Nebraska-LincolnFollow
Shuangye Yin, Georgia Institute of Technology
Ramiro Moro, Georgia Institute of Technology
Anthony Liang, Georgia Institute of Technology
John Bowlan, Georgia Institute of Technology
Walt A. de Heer, Georgia Institute of Technology

Date of this Version

2011

Document Type

Article

Citation

PRL 107, 057203 (2011)

Comments

Used by permission.

Abstract

Homonuclear cobalt and iron clusters Co_N and Fe_N measured in a cryogenic molecular beam exist in two states with distinct magnetic moments (μ), polarizabilities, and ionization potentials, indicating distinct valences. The μ is approximately quantized: μ_N ~ 2Nμ_B in the ground states and μ_N* ~ Nμ_B in the excited states for Co; μ_N ~ 3N μ_B and μ_N * ~ Nμ_B for Fe. At a large size, the average μ of the two states converges to the bulk value with diminishing ionization potential differences. The experiments suggest localized ferromagnetism in the two states and that itinerant ferromagnetism emerges from their superposition.