Magnetic coupling of Fe-porphyrin molecules adsorbed on clean and c ( 2 × 2 ) oxygen-reconstructed Co(100) investigated by spin-polarized photoemission spectroscopy

The spin-polarized electronic structure of iron octaethylporphyrin (FeOEP) molecules adsorbed on a pristine and on a c (2 x 2) oxygen-reconstructed Co(100) surface has been analyzed by means of spin-polarized photo-emission spectroscopy (SPPES) and first-principles density functional theory with the on-site Coulomb repulsion U term (DFT + U) calculations with and without Van der Waals corrections. The aim is to examine the magnetic exchange mechanism between the FeOEP molecules and the Co(100) substrate in the presence or absence of the oxygen mediator. Microspot low-energy electron diffraction and low-energy electron microscopy were performed to characterize the physical order of the molecular coverage, revealing that FeOEP structural domains are orders of magnitude greater in size on c (2 x 2)O/Co(100) than on clean Co(100), which coincides with reduced scattering from the disorder and sharper features seen in SPPES.