Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 54: Electronic structure II
O 54.4: Vortrag
Mittwoch, 24. März 2010, 15:45–16:00, H33
Stabilization of bulk-like α-Mn on W(110): LEED, PES, and DFT studies — •Elena Voloshina1, Yuriy Dedkov2, and Manuel Richter3 — 1Freie Universität Berlin, Germany — 2Fritz-Haber Institut der Max-Planck Gesellschaft, Berlin, Germany — 3IFW Dresden, Germany
Manganese can be considered as the most complex of all metallic elements from the crystallographic point of view. Assuming regular structural trends as in the series of the 4d and 5d transition metals, one would expect crystallization of Mn in a hcp structure. Being a member of the 3d-row where elements crystallize in bcc, fcc, or hcp structures, Mn behaves in a completely different way. Depending on temperature and pressure, it exists in five allotropic forms [1]. α-Mn, the stable phase below 1000K, has an exotic bcc crystal structure containing 58 atoms in the conventional cubic unit cell. Here we demonstrate a successful stabilization of bulk-like α-Mn films with (110) orientation on W(110). The (3 x 3) overstructure observed for the Mn film with respect to the original W(110) LEED pattern is consistent with the suggested structural model. Density functional total energy calculations confirm that this structure, a strained α-Mn phase, is close in energy to the ground state phase and thus can be prepared under carefully controlled conditions. It is metastable, though, and can be destroyed by annealing at 300∘C. Angle-resolved PE spectra show weak but distinct dispersions of the electronic states in the valence band that confirm a high quality of the studied Mn films.
[1] J. Hafner et al. PRB 68, 014407 (2003); PRB 68, 014408 (2003).