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DF: Fachverband Dielektrische Festkörper

DF 3: Dielectric and ferroelectric thin films 2

DF 3.3: Talk

Monday, March 14, 2011, 15:50–16:10, MÜL Elch

Tunneling through ferroelectrics: the role of the electronic structure of the barrier — •Daniel Wortmann and Stefan Blügel — Peter Grünberg Institut and Institute for Advanded Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich

Some of the proposed novel functionalities of future oxide-based electronics will drive their physical origin in the use of ferroelectric materials for tunneling barriers. With different directions of the ferroelectric polarization the tunneling conductance is modified, thereby allowing to utilize the polarization state for data storage. In direct analogy to the tunneling-magneto-resistance (TMR) a tunneling-electro-resistance (TER) can be defined. One of the most basic microscopical sources of the TER is the change of the electronic transmission though the ferroelectric insulator because of the modified barrier potential.

We will discuss the basic theory of TER and we will demonstrate how a realistic description of the electronic structure as provided by density functional theory and the Green function formalism implemented in our FLEUR code [1,2] can be used to estimate the significance of the electronic structure of the barrier to the TER. We show that the change of the barrier potential in the simple prototype ferroelectric insulators BaTiO₃ and PbTiO₃ will lead to a very weak TER effect and thus the TER in junctions based on these materials will be dominated by interface effects.

[1] http://www.flapw.de

[2] D.Wortmann, H. Ishida and S. Blügel, PRB 66,075113 (02)