My Proposed research will be highlight on ‘Revealingmagnetic information from a thin layer surface by using the synchrotron X-ray scanningtunnelling microscopy”The real space observation of magneticstructure utilizing scanning probe microscopy (SPM) techniques orsynchrotron-based microscopy keeps on tremendously affecting our comprehensionof nanomagnetism.
Spin Polarized scanning tunneling microscopy (SP-STM) issensitive to the spin orientation of tunneling electrons, while magnetic forcemicroscopy (MFM) recognizes the forces between a magenitc specimen surface andmagnetic tip. Despite the fact that these strategies give high spatialresolution of specimen surface, they do not have direct chemical contrast. Onthe other hand, chemical and sensitivity can be proved by photoemission electronmicroscopy (PEEM). However, photoelectron emission angles restrict the spatialresolution.In order to conquer these restrictions, somegroups around the world have been developing instruments that combinesynchrotron radiation with the high spatial resolution of various SPM. As oflate, synchrotron X-ray scanning tunneling microscopy (SX-STM) demonstrated theability to acquire elemental contrast with 2nm of resolution. The SX-STM techniqueuses the energy-dependent absorption of X-rays to acquire information about thecomposition of a sample. Core electrons are excited in the absorption processinto empty states above the Fermi energy, while a specific tip is scanning overa specimen surface.
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In the meantime, auxiliary electrons are shot out from thesample surface. The two commitments, i.e. X-ray energized tunneling and photo ejectedelectrons, adjust the ordinary tunneling current and subsequently provide thechemical contrast.The research plan and methodology areproposed as follow:1. The Cu (111)surface will be cleaned by repeated cycle of Argon sputtering and annealing.2. Cobalt atoms willbe evaporated from electron beam evaporator to Cu (111) surface in the loadlockattached to SX-STM.
3. Localized spectroscopy withsimultaneous topographic, elemental and magnetic information will be studied byemploying the synchrotron X-ray scanning tunneling microscope. The localinvestigation of the X-ray magnetic circular dichroism(XMCD) at the Cobalt L2,3-edges of a thin cobalt film grown on Cu(111) will be carried out.4. Polarization dependent X-ray absorptionspectra will be obtained through a tunneling non-conductive tip as a photoelectrondetector.
Contradictory to conventional spin-polarized scanning tunnelingmicroscopy, X-ray excitations will provide magnetic contrast even with anon-magnetic tip. 5. Determination of topography andchemistry simultaneously as well as the potential will be done to measure theactual size of magnetic moments using the dichroism effect.