We develop a simple model to compute the energy-dependent decay factors of metal-induced gap states in metal/insulator interfaces considering the collective behavior of all the bulk complex bands in the gap of the insulator. The agreement between the penetration length obtained from the model (considering only bulk properties) and full first-principles simulations of the interface (including explicitly the interfaces) is good. The influence of the electrodes and the polarization of the insulator are analyzed. The method simplifies the process of screening materials to be used in Schootky barriers or in the design of giant tunneling electroresistance and magnetoresistance devices.
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The authors thank K. M. Rabe and M. H. Cohen for helpful discussion. This work was supported by the Spanish Ministery of Science and Innovation through the MICINN Grant FIS2009-12721-C04-02, by the Spanish Ministry of Education through the FPU fellowship AP2006-02958 (PAP), and by the European Union through the project EC-FP7, Grant No. CP-FP 228989-2 “OxIDes”. The authors gratefully acknowledge the computer resources, technical expertise, and assistance provided by the Red Española de Supercomputacion. Calculations were also performed at the ATC group of the University of Cantabria.
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Aguado-Puente, P., Junquera, J. First-principles study of metal-induced gap states in metal/oxide interfaces and their relation with the complex band structure. MRS Communications 3, 191–197 (2013). https://doi.org/10.1557/mrc.2013.43