My Proposed research will be highlight on ‘Revealing
magnetic information from a thin layer surface  by using the synchrotron X-ray scanning
tunnelling microscopy”

The real space observation of magnetic
structure utilizing scanning probe microscopy (SPM) techniques or
synchrotron-based microscopy keeps on tremendously affecting our comprehension
of nanomagnetism. Spin Polarized scanning tunneling microscopy (SP-STM) is
sensitive to the spin orientation of tunneling electrons, while magnetic force
microscopy (MFM) recognizes the forces between a magenitc specimen surface and
magnetic tip. Despite the fact that these strategies give high spatial
resolution of specimen surface, they do not have direct chemical contrast. On
the other hand, chemical and sensitivity can be proved by photoemission electron
microscopy (PEEM). However, photoelectron emission angles restrict the spatial
resolution.

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In order to conquer these restrictions, some
groups around the world have been developing instruments that combine
synchrotron radiation with the high spatial resolution of various SPM. As of
late, synchrotron X-ray scanning tunneling microscopy (SX-STM) demonstrated the
ability to acquire elemental contrast with 2nm of resolution. The SX-STM technique
uses the energy-dependent absorption of X-rays to acquire information about the
composition of a sample. Core electrons are excited in the absorption process
into empty states above the Fermi energy, while a specific tip is scanning over
a specimen surface. In the meantime, auxiliary electrons are shot out from the
sample surface. The two commitments, i.e. X-ray energized tunneling and photo ejected
electrons, adjust the ordinary tunneling current and subsequently provide the
chemical contrast.

The research plan and methodology are
proposed as follow:

1.   
The Cu (111)
surface will be cleaned by repeated cycle of Argon sputtering and annealing.

2.   
Cobalt atoms will
be evaporated from electron beam evaporator to Cu (111) surface in the loadlock
attached to SX-STM.

3.   
Localized spectroscopy with
simultaneous topographic, elemental and magnetic information will be studied by
employing the synchrotron X-ray scanning tunneling microscope. The local
investigation 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 absorption
spectra will be obtained through a tunneling non-conductive tip as a photoelectron
detector. Contradictory to conventional spin-polarized scanning tunneling
microscopy, X-ray excitations will provide magnetic contrast even with a
non-magnetic tip.

5.   
Determination of topography and
chemistry simultaneously as well as the potential will be done to measure the
actual size of magnetic moments using the dichroism effect.

x

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