The magnetism of wurtzite CoO nanoclusters

Abstract

The possibility that the apparent room temperature ferromagnetism, often measured in Co-doped ZnO, is due to uncompensated spins at the surface of wurtzite CoO nanoclusters is investigated by means of a combination of density functional theory and Monte Carlo simulations. We find that the critical temperature extracted from the specific heat systematically drops as the cluster size is reduced, regardless of the particular cluster shape. Furthermore the presence of defects, in the form of missing magnetic sites, further reduces $T_{\mathrm{C}}$. This suggests that even a spinodal decomposed phase is unlikely to sustain room temperature ferromagnetism in ZnO:Co.

References in corpus (4)

• Two magnetic regimes in doped ZnO corresponding to a dilute magnetic semiconductor and a dilute magnetic insulator
• Magnetic interactions in transition metal doped ZnO : An abinitio study
• Impurity-Ion pair induced high-temperature ferromagnetism in Co-doped ZnO
• Origin of ferromagnetism in (Zn,Co)O from magnetization and spin-dependent magnetoresistance

Cited by in corpus (2)

• Collinear and non-collinear spin ground state of wurtzite CoO
• Magnetic interaction of Co ions near the {10\bar{1}0} ZnO surface