Probing the surface phase diagram of Fe3O4(001) towards the Fe-rich limit: Evidence for progressive reduction of the surface

journal article - other

English

Reduced terminations of the Fe3O4(001) surface were studied using scanning tunneling microscopy, x-ray photoelectron spectroscopy (XPS), and density functional theory (DFT). Fe atoms, deposited onto the thermodynamically stable, distorted B-layer termination at room temperature (RT), occupy one of two available tetrahedrally coordinated sites per unit cell. Further RT deposition results in Fe clusters. With mild annealing, a second Fe adatom per unit cell is accommodated, though not in the second tetrahedral site. Rather both Fe atoms reside in octahedral coordinated sites, leading to a Fe-dimer termination. At four additional Fe atoms per unit cell, all surface octahedral sites are occupied, resulting in a FeO(001)-like phase. The observed configurations are consistent with the calculated surface phase diagram. Both XPS and DFT+U results indicate a progressive reduction of surface iron from Fe3+ to Fe2+ upon Fe deposition. The antiferromagnetic FeO layer on top of ferromagnetic Fe3O4(001) suggests possible exchange bias in this system.

Oxide surfaces; Iron Oxides, STM, DFT, XPS

NOVOTNÝ, Z.; MULAKALURI, N.; ÉDES, Z.; SCHMID, M.; PENTCHEVA, R.; DIEBOLD, U.; PARKINSON, G.

2013

8. 5. 2013

1098-0121

PHYSICAL REVIEW B

87

19

United States of America

195410-1

195410-8

8