Spin-polarized scanning tunneling microscopy on ultrathin iron films on Be(0001)

• Applicant: Dr. Stefan Krause
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2017 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 339482673

Within this project ultrathin iron films prepared on a Be(0001) surface under ultrahigh vacuum conditions will be investigated using spin-polarized scanning tunneling microscopy. We expect the iron film to continue the hexagonal close packed atomic lattice of the beryllium substrate, resulting in the Epsilon-phase of the iron structure. The magnetism of Epsilon-iron is not yet unambiguously clear and consequently subject of many ongoing scientific debates. So far, Epsilon-iron has been realized experimentally in bulk samples under extreme high pressure. Our approach allows for the first time the direct investigation of magnetism in ultrathin and extremely pure Epsilon-iron films with atomic precision. The lattice stress induced by the substrate simulates external pressure of up to several 100 GPa, resulting in a considerable compression of the Epsilon-iron film. With increasing film thickness the atomic lattice is expected to relax into the intrinsic Epsilon phase and finally into the conventional body centered cubic phase. At the Fe/Be(0001) interface interesting interactions are expected between the two-dimensional electron gas in beryllium and the local magnetic moments of the iron film, which will be decisive for the magnetic properties of the iron film. Spin-polarized scanning tunneling experiments will allow to access the magnetic state as a function of film thickness and temperature and therefore will shed new light onto the magnetism of Epsilon-iron.

• DFG Programme: Research Grants