Speaker
Dr
Aliakbar Ghafari
(Helmholtz Zentrum Berlin)
Description
By means of high resolution angle resolved photoemission spectroscopy (ARPES) the electronic structure of the semiconductor TlInSe2 is investigated across the reported structural phase transitions at 185 K and 135 K. The ARPES intensity maps along the $\Gamma-M$, $\Gamma-N$ and $\Gamma-Z$ directions of the Brillouin zone (BZ) at 300 K, 160 K, and 20 K reveal that the valence band maxima (VBM) are located at the M and Z-point of the BZ. A strong polarization effect was observed in TlInSe2 suppressing the intensity at the VBM at the M-point for horizontal polarization of light. Moreover, a sizeable spin-orbit splitting of the valence bands has also been observed. The absolute energies of the spin-orbit splitting of the valence bands (at $\Gamma:339meV$, $M:141meV$ and $Z:191meV$) are in good agreement with theoretical data based on density functional theory. The experimental band structure data measured at three different temperatures reveal that by cooling band splitting appears between valence bands as a consequence of the structural phase transitions in TlInSe2 compound.
Author
Dr
Aliakbar Ghafari
(Helmholtz Zentrum Berlin)
