Universidad Nacional Autónoma de México - CNyN

1st International Symposium on Nanoscience and Nanomaterials
O-004
TEMPERATURE DEPENDENCE OF THE SPIN POLARIZATION RESPONSE IN SPIN-ORBIT
COUPLED SYSTEMS
Priscilla E. Iglesias Vázquez 1,a and Jesús A. Maytorena Córdova 2,b
1 Posgrado en Física de Materiales, CICESE-UNAM. Ensenada, B.C., México.
2 Centro de Nanociencias y Nanotecnología, UNAM. Ensenada, B.C., México.
a piglesia@cnyn.unam.mx, b jesusm@cnyn.unam.mx
Keywords: spin polarization, spin-orbit interaction, semiconductor spintronics.
We investigate the temperature dependence of the electric field-induced spin polarization of a twodimensional
electron gas with Rashba and Dresselhaus spin-orbit interaction (SOI). The frequency-dependent
spin polarizability tensor for finite temperature is calculated using the linear-response theory; the cases of
quantum wells grown in the main crystallographic directions are considered. The spin splitting caused by SOI
opens the possibility of resonant effects involving electric-dipole transitions between the spin-split subbands
as a response to alternating electric fields in the THz regime. Due to the anisotropic character of the SOI, the
spin polarization response becomes dependent on the direction of the applied electric field and presents
characteristic spectral features only within the SO-induced energy window for optical absorption 1 ; this is in
contrast to the case of pure Rashba or Dresselhaus case. At non-vanishing temperature this behaviour is
modified, given that the optical inter-spin-split subbands transitions are then possible in a wider range of
energies, beyond the sharp T=0 absorption edges. As a consequence, the spin density response decreases
monotonically with temperature for frequencies outside the mentioned window. We also study the effect of a
temperature gradient in order to explore the spin Hall effect driven by the flow of heat. This raised new
possibilities for spin current generation by means of heat currents and vice versa. This work was supported by
DGAPA-UNAM IN114210 and CONACyT-México.
1 Iglesias, P.E. y Maytorena, J.A. Anisotropic dynamical spin-density response in quantum wells with spin-orbit interaction. Phys. Rev. B 82, 205324 (2010).
O-005
OPTICAL PROPERTIES OF TiO 2 /Al 2 O 3 NANOLAMINATES GROWN BY ATOMIC LAYER
DEPOSITION
Hugo Tiznado 1,a , Wencel de la Cruz 1,b , Gerardo Soto 1,c and David Domínguez 1,d
1 Centro de Nanociencias y Nanotecnología – UNAM, Ensenada, Mexico.
a tiznado@cnyn.unam.mx, b wencel@cnyn.unam.mx, c gerardo@cnyn.unam.mx, d david@cnyn.unam.mx
Keywords: atomic layer deposition, optical properties, thin films.
Composite films whose refractive index can be adjusted by mixing two materials at different ratios
are of considerable interest for optical and electronic applications [1]. In particular, those materials with
potential to replace SiO 2 , as the gate oxide in complementary metal–oxide–semiconductors (CMOS), are
currently being aggressively studied [2]. It is reported that the TiO 2 and Al 2 O 3 nanolaminates are able to tune
their refractive index (n) and the extinction coefficient (k) by varying their individual thickness. However,
only discrete values have been reported for specific light energies. In this work, it was employed the atomic
layer deposition (ALD) technique to prepare Al 2 O 3 /TiO 2 nanolaminates on silicon (111) substrates. The
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