Electronic structure and magnetic properties of the hcp Co(0001) surface

Results of a spin polarized full potential linearized augmented plane wave (FLAPW) study of the hcp Co(0001) surface is reported. The calculated surface magnetic moment (≈1.76μ_B) is enhanced by ≈7% from the calculated bulk value (≈1.64μ_B) and by ≈9% from the experimental bulk value (≈1.57μ_B), a result of the narrowing of the 3d electron bands at the surface. In this system, the surface effect is seen to extend into the second atomic layer below the surface, in contrast with the one layer range found for the non-close-packed cobalt surfaces (e.g., bcc or fcc (001)). As estimated from the total energy calculations, the surface energy of hcp Co(0001) is ≈2 J/m².