Magnetic reconstruction at (001) CaMnO$_3$ surface

TL;DR

This paper investigates magnetic reconstruction at the (001) surface of CaMnO₃, revealing a spin-flip process driven by e_g state redistribution, which could impact understanding of CMR materials.

Contribution

It uncovers a surface magnetic reconstruction in CaMnO₃ driven by e_g state redistribution, highlighting a double exchange-like coupling without significant charge transfer.

Findings

Surface Mn spins flip at the (001) surface.

Magnetic reconstruction driven by e_g state redistribution.

Potential implications for CMR materials.

Abstract

The Mn-terminated (001) surface of the stable anti-ferromagnetic insulating phase of cubic perovskite CaMnO$_3$ is found to undergo a magnetic reconstruction consisting on a spin-flip process at surface: each Mn spin at the surface flips to pair with that of Mn in the subsurface layer. In spite of very little Mn-O charge transfer at surface, the surface behavior is driven by the $e_g$ states due to $d_{xy}$ $\to$ $d_{z^2}$ charge redistribution. These results, based on local spin density theory, give a double exchange like coupling that is driven by $e_g$ character, not additional charge, and may have relevance to CMR materials.