Surface electronic and magnetic properties of La2/3Sr1/3MnO3 thin films with extended metallicity above the Curie temperature

The surface electronic and magnetic properties of epitaxial La(2/3)Sr(1/3)MnO(3)/SrTiO(3)(001) films with extended bulk metallicity above the Curie temperature have been investigated. By angle-resolved photoemission we show that the surface electronic structure presents the e(g) dispersing band, responsible for the half-metallicity, crossing the Fermi level and leading to a sharp Fermi edge. Quasiparticle excitations, reflecting the coherent polaronic ferromagnetic and metallic ground state, are clearly visible at the Fermi level and 16 K, while they disappear at room temperature, where a Fermi edge is still clearly visible. X-ray magnetic circular dichroism shows a robust subsurface magnetization up to T(C), while spin-polarization Mott spectroscopy indicates a rapid suppression of the surface magnetization which disappears around room temperature. These results clearly demonstrate that a robust surface metallic electronic structure does not necessarily ensure the concomitant stabilization of long-range magnetic order.