Abstract
At interfaces of certain oxides with an ABO3 perovskite structure, a
2d electron gas is formed. In this project, the interface of LaAlO3(LAO)
and SrTiO3(STO) is examined. This structure is grown on a substrate
of bulk NdGaO3(NGO) so as to inuence the crystal structure of the
LAO. The di_erence in the crystal _eld parameters causes strain on the
structure of the LAO and STO which causes the octahedral symmetry
to break and change to tetragonal symmetry. A direct result of this is
existence of an energy splitting between the t2g (xz, yz and xy) and eg
(z2 and x2-y2) d-orbitals of the Ti in SrTiO3. Values of the splitting of
the t2g and eg orbitals have been extracted from theoretical simulations
of linearly polarized X-ray absorption (XAS) data recorded at the L2 and
L3 edges of Ti in these thin _lm systems by two groups. The XAS spectra
are divided into horizontal and vertical polarizations to calculate the XRay Linear Dichroism (XLD). XLD measurements are valuable in this
context as they are sensitive to the local symmetry around the Ti sites and
therefore can act as a signal of structural deformations or reconstructions.
Only when all 3 spectra (XAS horizontal, XAS vertical and XLD) are a
good _t to the theoretical spectra, can reliable values for the crystal _eld
parameters Dt and Ds be extracted. These values translate to values of
_t2g and _eg, which are the energy splittings involved. In this thesis an
overview of theoretical calculations are compared to experimental data
from 2 di_erent sources to _nd values of the orbital splitting.