page_title: Spin polarized scanning tunneling microscopy
section_title: Applications of SP-STM
hierarchical_section_title: Spin polarized scanning tunneling microscopy / Applications of SP-STM
caption_attribution_description: English: Spin-averaged image obtained by scanning tunneling spectroscopy for Co nano islands formed on Cu(111)
context_page_description: Spin-polarized scanning tunneling microscopy is a specialized application of scanning tunneling microscopy that can provide detailed information of magnetic phenomena on the single-atom scale additional to the atomic topography gained with STM. SP-STM opened a novel approach to static and dynamic magnetic processes as precise investigations of domain walls in ferromagnetic and antiferromagnetic systems, as well as thermal and current-induced switching of nanomagnetic particles.
context_section_description: The spin polarized scanning tunneling microscope is a versatile instrument which has gained tremendous attention due to its enhanced surface sensitivity and lateral resolution up to atomic scale, and can be used as an important tool to study ferromagnetic materials, such as Dysprosium (Dy), quasi-2D thin films, nano islands and quasi-1D nanowire that have high magnetic anisotropy, etc. In a study carried out by L. Berbil-Bautista et al., the magnetic domain wall or Néel wall of the width 2-5 nm present in these materials is observed by bringing the Chromium (Cr) coated Tungsten tip close to the Dy layer. This causes the transfer of Dy particles from magnetic material on to the apex of the tip. The width of the domain wall is calculated as
   where  is exchange stiffness. The magnetic contrast is enhanced due to the presence of electronic states that are not occupied in the cluster of Dy atoms present on the apex of the tip.
  The formation of 360° domain walls in ferromagnetic films plays an important role in making magnetic random access memory devices. These domain walls are formed when an external magnetic field is applied along the easy direction of magnetic material. This forces the two 180° walls, which also have identical sense of rotation to come closer. In a study carried out by A. Kubetzka et al., the SP-STM was used to measure the evolution of 360° domain wall profiles of two atomic layer iron nanowires by varying the external magnetic field between 550-800 mT.
  The quantum interference phenomena has been observed in Cobalt islands deposited on Copper(111) substrate. This has been attributed to the fact that scattering caused by surface state electron defects, such as terrace edges, impurities or adsorbates present on a densely packed noble metal surface. Spin polarized-STM has been used to investigate the electronic structure of triangular Cobalt islands deposited on Copper(111). This study shows that the substrate and islands exhibit their individual standing wave patterns and this can be used to find the spin polarized material.
caption: Spin-averaged image obtained by scanning tunneling spectroscopy for Cobalt nano islands formed on Cu(111).
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