Abstract
The formation energy and local magnetic moment of a series of point defects in are computed using a supercell approach within the generalized gradient approximation to density functional theory. It is found that the substitution of Ca by La does not lead to the formation of a local moment, while a neutral vacancy carries a moment of 2.4 Bohr magnetons. A plausible mechanism for the ferromagnetic ordering of these moments is suggested. Since the same broken B—B bonds appear on the preferred (100) cleavage planes of the structure, it is argued that internal surfaces in polycrystals as well as external surfaces in general will make a large contribution to the observed magnetization.
- Received 11 May 2001
DOI:https://doi.org/10.1103/PhysRevLett.87.157204
©2001 American Physical Society