### Session V43: Low Dimensional Magnetism: Clusters & Molecules

11:15 AM–1:51 PM, Thursday, March 24, 2005
LACC Room: 150C

Chair: V. Kiryukhin, Rutgers University

Abstract ID: BAPS.2005.MAR.V43.2

### Abstract: V43.00002 : Mn clusters: a nanoscale magnetic transition

11:27 AM–11:39 AM

Preview Abstract MathJax On | Off   Abstract

#### Authors:

Sudha Srinivas
Koblar A. Jackson
Small Mn clusters exhibit remarkable magnetic behavior. Early ESR experiments[1] found the smallest clusters (n=2-5) to be ferromagnetic (FM), while later Stern-Gerlach measurements[2] found larger clusters (n$>$12) to have very small net moments. Our calculations show that these data reflect a transition in magnetic \textit{ordering} as a function of cluster size, occurring at n=7 atoms. Specifically, the FM arrangements of the atomic spins favored in smaller clusters give way to antiferromagnetic (AF) arrangements in larger clusters. We find that the FM $\to$ AF transition occurs at n=7, in agreement with experimental data, and is driven by a large change in the relative energies of the FM and AF structures. We present results for the structures and magnetic properties of Mn$_{n}$ (n = 2-13), focusing on correlations between the structural, electronic and magnetic properties of the clusters and discuss the effect of substitutional impurities on the magnetic properties of the clusters. \begin{enumerate} \item C. A. Baumann et al., J. Chem. Phys. \textbf{78}, 190 (1983). \item M. B. Knickelbein, Phys. Rev. Lett. \textbf{86}, 5255 (2001). \end{enumerate}