1212.5038 (F. Cossu et al.)

Surface antiferromagnetism and incipient metal-insulator transition in
strained manganite films    [PDF]

F. Cossu, U. Schwingenschlögl, G. Colizzi, A. Filippetti, Vincenzo Fiorentini

Using first-principles calculations, we show that the (001) surface of the ferromagnet La$_{1-x}$Sr$_{x}$MnO$_{3}$ under epitaxial compression favors antiferromagnetic ordering in the first few surface layers, coexisting with ferromagnetic bulk order. The change in magnetic order is accompanied by a marked surface-related spectral pseudogap, signaling a metal-insulator near-transition at the surface. All surfaces exhibit huge outward relaxations an rumpling of the MnO$_{2}$ and LaO surface planes, causing a distinct shift in work function. The AF phase is an extreme surface-assisted case of the combination of in-plane AF super-exchange and vertical FM double-exchange couplings that rules magnetism in manganites under in-plane compression.

View original: http://arxiv.org/abs/1212.5038