IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Magnetic Interfaces and Nanostructures Friday Sessions
       Session MI+SS-FrM

Paper MI+SS-FrM3
Surface Structure and Phase/Orientation Control of Manganese Nitride Grown by Molecular Beam Epitaxy

Friday, November 2, 2001, 9:00 am, Room 110

Session: Magnetic Thin Films and Surfaces II
Presenter: H. Yang, Ohio University
Authors: H. Yang, Ohio University
H.A.H. Al-Brithen, Ohio University
A.R. Smith, Ohio University
R.L. Cappelletti, National Institute of Standards and Technology
J.A. Borchers, National Institute of Standards and Technology
M.D. Vaudin, National Institute of Standards and Technology
Correspondent: Click to Email
We have investigated the growth of manganese nitride on MgO(001) substrates using molecular beam epitaxy (MBE) and have studied the surfaces using scanning tunneling microscopy (STM). Manganese nitride has many bulk phases (labeled @theta@, @eta@, @zeta@, and @epsilon@). Using MBE, we can individually select these phases by controlling the growth parameters. For example, at low Mn flux, we obtain the N-rich @theta@ phase (MnN), which has fct structure;@footnote 1@ but at increased Mn flux, we obtain the less N-rich @eta@-phase (Mn3N2) which is also fct but includes ordered arrays of N vacancies, according to a model proposed by Kreiner and Jacobs.@footnote 2@ Neutron scattering confirms that the Mn moments are aligned in a layered antiferromagnetic arrangement. By adjusting the growth parameters, we are able to control not only the phase, but also the crystalline orientation. At low Mn flux, the @eta@-phase has its c-axis perpendicular to the growth surface (@eta@1). But at yet higher Mn flux, the c-axis is oriented parallel to the surface (@eta@2), a consequence being two equivalent domains, D1 and D2, at 90° to each other. These domains are evident during growth via RHEED, which shows two closely spaced 1st-order streaks due to the fct structure. Also, 1/3-order lines are observed due to the periodic vacancy planes which are normal to the surface. STM images following growth clearly reveal the two domains at the @eta@2 surface. Row structures corresponding to the vacancy planes are clearly observed. Atomic resolution images show enhancement for the Mn atoms at the intersections of the surface and vacancy planes. This is likely related to the fact that these Mn have fewer N neighbors compared to other surface Mn atoms. This work is supported by NSF. @FootnoteText@ @footnote 1@ Suzuki et al., J. Alloys and Compounds 306, 66 (2000), @footnote 2@ Kreiner and Jacobs, J. Alloys and Compounds 183, 345 (1992).