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Trinity College Dublin

Electronic transport properties fo transition-metal/SrTiO3(100) heterojunctions

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Prof. Stefano Sanvito
Perovskite oxides have attracted increasing interest in science and technology as potentialalternatives to various silicon-based microelectronic components. Strontium titanate (STO) isa representative perovskite oxide that can be used as a dielectric in thin-film capacitors orfield-effect devices. One of the crucial characteristics of these microelectronic devices is theleakage current. From experiments it is evident that leakage currents vary over many orders ofmagnitude depending on the electrode metal and on external conditions such as temperatureand applied voltage.Since the perovskite oxides are insulating materials with a relatively small band gap (typicallyaround 3.5 eV), the thermionic emission is considered as one of the primary sources of leakagecurrent. This conduction mechanism is directly related to the Schottky barrier (SB) that formsat the interface between the dielectric and the electrode.In order to perform a systematic study of the SB-dependence on the structure and composi-tion of the dielectric-electrode interfaces, we have calculated the SB-heights (SBH) for va-rious transition-metal/STO(100) interfaces using a mixed-basis pseudopotential approach ofdensity-functional theory (see [2],[1] and references therein). For a precise analysis of SBformation mechanisms we used a step-by-step procedure, which enables to distinguish thecontributions due to atomic and electronic rearrangements [2].The aim of our future work is to investigate the transmission probability across the hetero-junctions, which is related to the quantum conductance. Calculations will be done using theS MEAGOL package that is based on a non-equilibrium Green’s function formalism for phase-coherent transport [3, 4]. This method also enables to examine the dependence of the SBH andits contributing mechanisms on the applied voltage.In order to increase my proficiency of the S MEAGOL package I would like to visit the groupof Prof. Sanvito at the Trinity College in Dublin. Prof. Sanvito is one of the S MEAGOL devel-opers. His group has studied electronic transport properties of magnetic Fe/MgO(100) tunneljunctions as well as the ferromagnetic perovskite oxide strontium ruthenate. He has broad ex-perience and knowledge in this research field and I believe that I could greatly profit from thisvisit.
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