Magneto-electric coupling at metallic surfaces

• Applicants: Professor Dr. Arthur Ernst; Professor Dr. Wulf Wulfhekel
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2011 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 191444816

• Final Report Year: 2017

Final Report Abstract

The main result of our combined experimental and theoretical studies is that the magnetoelectric coupling is possible not only in insulators but also in metallic systems. However, this effect is only possible in the surface vicinity when the surface charge density can be affected strongly by an applied electric field. This interaction can lead to substantial relaxations of the layers in the surface vicinity and, if magnetic properties of the layers are sensitive enough to the structural changes, can alter the magnetic order of the film. In many aspects, an iron thin film is an appropriate candidate for possible devices based on this effect. The reasons are: (i) Fe is magnetic and (ii) Fe is a magneto-elastic material, which magnetic properties are strongly affected by structural relaxations. We have shown as well that interpretation of STM/STS spectroscopy measurements is of a careful task due to a strong orbital-dependent decay length of the wave function at the surface. An important part of the project was a significant code development, which enabled to take into account an applied electric field for realistic simulations of STM/STS spectroscopies.

Publications

• Thickness-dependent electronic and magnetic properties of γ’-Fe4 N atomic layers on Cu(001)
  Y. Takahashi, T. Miyamachi, S. Nakashima, N. Kawamura, Y. Takagi, M. Uozumi, V. Antonov, T. Yokoyama, A. Ernst, and F. Komori
  
• Electrical Control of the Magnetic State of Fe, IEEE Transactions on Magnetics 47, 1619-1622 (2011)
  L. Gerhard, T.K. Yamada, T. Balashov, A.F. Takacs, R.J.H. Wesselink, M. Däne, M. Fechner, S. Ostanin, A. Ernst, I. Mertig, W. Wulfhekel
  
• Magnetic Excitations of Rare Earth Atoms and Clusters on Metallic Surfaces, Nano Lett. 12, 4805-4809 (2012)
  T. Schuh, T. Miyamachi, S. Gerstl, M. Geilhufe, M. Hoffmann, S. Ostanin, W. Hergert, A. Ernst, and W. Wulfhekel
  
• Band Structure Engineering in Topological Insulator Based Heterostructures, Nano Lett. 13, 6064-6069 (2013)
  T. V. Menshchikova, M. M. Otrokov, S. S. Tsirkin, D. A. Samorokov, V. V. Bebneva, A. Ernst, V. M. Kuznetsov, and E. V. Chulkov
  
• Dynamics of Electrically Driven Martensitic Phase Transition in Fe, Physical Review Letters 111, 167601 (2013)
  L. Gerhard, R.J.H. Wesselink, S. Ostanin, A. Ernst, W. Wulfhekel
  
• Orbital Selectivity in Scanning Tunneling Microscopy: Distance-Dependent Tunneling Process Observed in Iron Nitride, Physical Review Letters 116, 056802 (2016)
  Y. Takahashi, T. Miyamachi, K. Ienaga, N. Kawamura, A. Ernst, and F. Komori