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High Mobility in LaAlO3/SrTiO3 Heterostructures: Origin, Dimensionality and Perspectives

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 نشر من قبل Gervasi Herranz
 تاريخ النشر 2007
  مجال البحث فيزياء
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We have investigated the dimensionality and origin of the magnetotransport properties of LaAlO3 films epitaxially grown on TiO2-terminated SrTiO3(001) substrates. High mobility conduction is observed at low deposition oxygen pressures (PO2 < 10^-5 mbar) and has a three-dimensional character. However, at higher PO2 the conduction is dramatically suppressed and nonmetallic behavior appears. Experimental data strongly support an interpretation of these properties based on the creation of oxygen vacancies in the SrTiO3 substrates during the growth of the LaAlO3 layer. When grown on SrTiO3 substrates at low PO2, other oxides generate the same high mobility as LaAlO3 films. This opens interesting prospects for all-oxide electronics.



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LaAlO3/SrTiO3 structures showing high mobility conduction have recently aroused large expectations as they might represent a major step towards the conception of all-oxide electronics devices. For the development of these technological applications a full understanding of the dimensionality and origin of the conducting electronic system is crucial. To shed light on this issue, we have investigated the magnetotransport properties of a LaAlO3 layer epitaxially grown at low oxygen pressure on a TiO2-terminated (001)-SrTiO3 substrate. In agreement with recent reports, a low-temperature mobility of about 10^4 cm2/Vs has been found. We conclusively show that the electronic system is three-dimensional, excluding any interfacial confinement of carriers. We argue that the high-mobility conduction originates from the doping of SrTiO3 with oxygen vacancies and that it extends over hundreds of microns into the SrTiO3 substrate. Such high mobility SrTiO3-based heterostructures have a unique potential for electronic and spintronics devices.
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