Magnetic reconstruction at the (001) CaMnO3 surface

The Mn-terminated (001) surface of the stable antiferromagnetic insulating phase of the cubic perovskite CaMnO3 is found to undergo a magnetic reconstruction consisting of a spin-flip process at the surface: Each Mn spin at the surface hips to pair with one in the subsurface layer. In spite of very little Mn-O charge transfer at the surface, the behavior is driven by the e(g) states due to the d(xy) --> d(z2) charge redistribution. These results, based on local spin density theory, give a double-exchange-like coupling that is driven by the e(g) character, not the additional charge, and may have relevance to colossal magnetoresistive materials.