Structure, electronic and magnetic properties of metal nanowires

• Applicants: Professor Dr. Wolfram Hergert; Professor Dr. Valeri Stepanyuk
• Subject Area: Theoretical Condensed Matter Physics
• Term: from 2004 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5437878

• Final Report Year: 2007

Final Report Abstract

Nowadays, nanosystem of enormous interest are atomic chains, nanocontacts, nanowires and stripes. Such one-dimensional (1D) systems are believed to possibly play a leading role in future electronic devices. Because of the giant magnetic anisotropy energy, 1D magnetic systems could also be very interesting for spintronics applications. Recent studies suggest that 1D spin chains could be used for quantum communications. Our project is devoted to ab initio studies of structure, electronic and magnetic properties of nanowires, chains and nanocontacts. The interplay between the structure, magnetism and electronic transport in such nanosystems is one of the main goals of our project. We investigate electronic processes on surfaces which can lead to the self-organized growth of nanowires. For example, our calculations and experiments have demonstrated that surface-state electrons on noble metal surfaces can be exploited to grow new 1D structures at low temperatures. Our first results indicate that it could be possible to use the quantum confinement between nanowires for growth of new 1D structures. We study exchange interactions in wires and between wires on clean and stepped metal surfaces. Obviously, the challenge would be to tailor such interactions. Magnetoelectronic devices, both existing and envisioned, rely on spin-dependent transport of electrons. Electronic transport is changed dramatically in constrained geometries of the nanometer scale when the dimensions are reduced to less than the mean free path of electrons. Very recent experiments have revealed the oscillatory nature of magnetoresistance as a function of contact size. We will study spin-dependent transport in quantum contacts of different sizes and compositions performing ab initio calculations for realistic geometrical structures.

Publications

• Atomic relaxations and magnetic states in a single-atom tunneling junction. Phys. Rev. B 73, 153404 (2006)
  R. Z. Huang, V. S. Stepanyuk, A. L. Klavsyuk, W. Hergert, P. Bruno, and J. Kirschner
  
• Effect of the long-range adsorbate interactions on the atomic self-assembly on metal surfaces. Surf. Sci. 600, L58 (2006)
  N. N. Negulyaev, V. S. Stepanyuk, W. Hergert, H. Fangohr, and P. Bruno
  
• Parity oscillation and relaxation in monoatomic copper wires. Phys. Rev. B 74, 115108 (2006)
  M. Czerner, A. Bagrets, V. S. Stepanyuk, A. L. Klavsyuk, and I. Mertig
  
• Effect of quantum confinement of surface electrons on adatom-adatom interactions. New J. Phys. 9, 388 (2007)
  V. S. Stepanyuk, N. N. Negulyaev, L. Niebergall, and P. Bruno
  
• Electronic confinement on stepped Cu(111) surfaces: Ab initio study. Phys. Rev. B 75, 155428 (2007)
  P. A. Ignatiev, V. S. Stepanyuk, A. L. Klavsyuk, W. Hergert, and P. Bruno
  
• Exchange interaction between single magnetic adatoms. Phys. Rev. Lett. 98, 056601 (2007)
  P. Wahl, P. Simon, L. Diekhöner, V. S. Stepanyuk, P. Bruno, M. A. Schneider, and K. Kern
  
• Self-organized long-period adatom strings on stepped metal surfaces: Scanning tunneling microscopy, ab initio calculations and kinetic Monte Carlo simulations. Phys. Rev. B 76, 033409 (2007)
  H. F. Ding, V. S. Stepanyuk, P. A. Ignatiev, N. N. Negulyaev, L. Niebergall, M. Wasniowska, C. L. Gao, P. Bruno, and J. Kirschner
  
• Structural and magnetic properties of Co chains on a stepped Cu surface. J. Phys. Cond. Matter 19, 446001 (2007)
  S. Pick, P. A. Ignatiev, W. Hergert, V. S. Stepanyuk, and P. Bruno