Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 17: Low-Dimensional Systems: Oxide Hetero-Interfaces
TT 17.6: Vortrag
Montag, 7. März 2016, 16:30–16:45, H22
Pressure effects on the 2D electron system in LaAlO3/SrTiO3. — •Vladislav Borisov1, Jone Zabaleta2, Harald O. Jeschke1, Thilo Kopp3, and Roser Valenti1 — 1Institute of Theoretical Physics, Goethe University, D-60438 Frankfurt am Main, Germany — 2Max Planck Institute for Solid State Research, D-70569 Stuttgart, Germany — 3Center for Electronic Correlations and Magnetism, Experimental Physics VI, Institute of Physics, University of Augsburg, D-86135 Augsburg, Germany
We present a theoretical study of pressure effects on the electronic
properties of the LaAlO3/SrTiO3 (001) interface. Lattice relaxation plays
a crucial role for the formation of the 2D electron system (2DES),
in agreement with previous reports.
We observe that the carrier density of the 2DES at zero pressure is
much lower than the “polar catastrophe” estimate of 0.5 e− per
two-dimensional unit cell, which agrees with most experimental works.
Under hydrostatic pressure, structural distortions in LaAlO3 (LAO)
are largely suppressed, whereas they increase in SrTiO3 (STO), and
the carrier density of the 2DES is enhanced by almost 45% using a moderate pressure of
4.1 GPa. The origin of this behavior as well as the explanation for
the low carrier density at the interface at ambient pressure are
discussed in terms of the lattice polarization and electronic Berry
phase in the LAO oxide. Reduction of the calculated static
dielectric constants of LAO and STO under pressure might account for
the recent experimental findings [1] regarding the carrier mobility.
J. Zabaleta et al. (in preparation).