AVS 52nd International Symposium
    Surface Science Tuesday Sessions
       Session SS1-TuA

Paper SS1-TuA3
Scanning Tunneling Microscopy Study of Square Manganese Tetramers on Mn3N2(001)

Tuesday, November 1, 2005, 2:40 pm, Room 202

Session: Compound Semiconductors
Presenter: R. Yang, Ohio University
Authors: R. Yang, Ohio University
H.Q. Yang, Ohio University
A.R. Smith, Ohio University
Correspondent: Click to Email
The growth of transition metal nitride layers has been a subject of significant interest due to their unique electronic, magnetic, and structural properties. We have previously investigated the growth of Mn3N2 on MgO(001) by molecular beam epitaxy (MBE).@footnote 1@ Mn3N2 is a layer-wise antiferromagnet with magnetic moments of ~ 3 mu_B.@footnote 2@ Two orientations ((010) and (001)) of this structure were grown controllably on MgO(001),depending on the growth conditions. As the bulk structure corresponds to 2 layers of MnN followed by 1 layer of Mn in a fct arrangement, scanning tunneling microscopy (STM) shows that the (010) surface consists of row structures.@footnote 3@ These rows correspond to the Mn planes, which are perpendicular to the surface. Here we present results for the (001) surface in which the Mn planes are in the surface plane. However, this presents an interesting question regarding the epitaxial Mn3N2 (001) growth surface, due to the MnN-MnN-Mn stacking sequence of the atomic layers in bulk. If the stacking sequence extends to the surface, then different structures should be observed on adjacent terraces. Again, these films are grown on MgO(001) substrates by MBE. STM images show smooth terraces and atomic steps. On certain of the terraces a unique and new reconstruction is seen, resolved as square Mn tetramers in a c(4x2) structural arrangement. Two domains of the tetramer reconstruction, rotated by 90 deg to each other, occur. A model is presented for this square Mn tetramer reconstruction, in which the Mn atoms of the tetramer layer belong to the Mn layer at the surface in the MnN-MnN-Mn stacking sequence. @FootnoteText@ @footnote 1@Yang et al., J. Appl. Phys. 91(3), 1053 (2002). @footnote 2@G. Kreiner, and H. Jacobs, J. Alloys and Comp. 183, 345 (1992). @footnote 3@Yang et al., Appl. Phys. Lett. 78, 3860 (2001). .