LMA

Magnetism on surfaces – Spin Polarized STM

  Magnetism on surfaces – Spin Polarized STM

 

In  this research area, we work in this two fields:
  • Atomic Magnetism and Manipulation:
    Left: overview of the construction site showing the Ag atoms protusions created in-situ with the tip, from where the atoms used in the manipulation were dragged out. Right: zoom in of the artificial atomic structure prepared at 4.8 K at two different tunneling energies

    Left: overview of the construction site showing the Ag atoms protusions created in-situ with the tip, from where the atoms used in the manipulation were dragged out. Right: zoom in of the artificial atomic structure prepared at 4.8 K at two different tunneling energies

    The unique capability of STM techniques are being exploited to alter the matter in the atomic or molecular scale with simultaneous electronic and magnetic characterization with atomic resolution. Recent developments on this field point to the possibility of downscaling stable magnetic moments to the scale of a single atom or artificial nanostructures constructed in an atom-by-atom fashion. The profound implications in magnetic data storage lead this research line to pursues a pioneering understanding of low dimensional magnetism using single atomic spins as building blocks of our sample system.
    Experiments are being conducted to explore interactions among neighboring atoms. The magnetic playground which enables a direct control of the atomic spin is the combined action of magnetocrystalline anisotropy, quantum fluctuations, and various exchange interactions with the substrate. Investigations address atomic nanostructures, constructed through controlled atomic manipulation, and magnetic adatoms deposited on ultra-thin insulating thin films, acting as spacers between adatom and substrate.
    A particular challenge is using atoms with large values of the intrinsic magnetic anisotropy (large spin orbit coupling) in the fabrication of magnetic structures formed by simply a few atoms. The adsorption and manipulation of rare-earth adatoms on the W(110) surface are being explored. The electronic state of the free ion is expected to be retained at the single atom scale, offering the possibility to study the magnetism of a lanthanide with 13 electrons in the f shell.
    The magnetic playground which enables a direct control of the atomic spin is the combined action of magnetocrystalline anisotropy, quantum fluctuations, and various exchange interactions wih the substrate. One example of atom-by-atom nanostructuring technique is the number “1” built with Ag atoms.
  • Rare Earth nanostructures:
    The goal of this line is the study of the competing interactions (dipolar, elastic, electronic,…) that are responsible for the self-organization of metal-on-metal systems, with special emphasis on rare earth adatoms. The socreated self-organization may give rise to individual atom arrays, as well as to extended nanostructures with different dimensionality, depending on the specific preparation procedure. These systems can be therefore envisaged to have an interesting outcome of quantum size effects in the electronic and magnetic properties of such nanostructures, with the goal of raising the superparamagnetic limit by tuning the shape of the magnetic nano-object at the atomic length scale.
    The preparation procedure of materials is characterized well below the monolayer, which becomes important in order to obtain long-range self organized materials instead of an assembly of defective polycrystalline arrays of nanoparticles. Current investigations focus on rare earths deposited at room temperature on W(110), well below one monolayer. W(110) is particularly interesting because it provides a structural anisotropy, steering the growth of one dimensional metal systems.