Abstract
We investigate theoretically the prospects of ferromagnetism being induced by cation vacancies in nonmagnetic oxides. A single Ca vacancy has a magnetic moment due to its open-shell structure but the ferromagnetic interaction between two vacancies extends only to four neighbors or less. To achieve magnetic percolation on a fcc lattice with such an interaction range one needs a minimum of 4.9% vacancies, or a concentration . Total-energy calculations for CaO show, however, that due to the high vacancy formation energy even under the most favorable growth conditions one can not obtain more than 0.003% or vacancies at equilibrium, showing that a nonequilibrium vacancy-enhancement factor of is needed to achieve magnetism in such systems.
- Received 3 November 2005
DOI:https://doi.org/10.1103/PhysRevLett.96.107203
©2006 American Physical Society