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Abstract:
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We have embarked on a systematic study of novel charge states at oxide interfaces . We have performed pulsed laser deposition (PLD ) growth of epitaxial oxide thin films on single crystal oxide substrates . We studied the effects of epitaxial strain and rare -earth composition of the metal oxide thin films . We have successfully created TiO₂ terminated SrTiO₃ (STO ) substrates and have grown epitaxial thin films of LaAlO₃ (LAO ) , LaGaO₃ (LGO ) , and RAlO₃ on STO using a KrF pulsed excimer laser . Current work emphasizes the importance of understanding the effect of both epitaxial strain and R³+ magnetism on the interface between RAlO₃ and STO . We have demonstrated that the interfaces between LAO /STO and LGO /STO are metallic with carrier concentrations of 1 .1 x 10¹⁴ cm[superscript -2] and 4 .5 x 10¹⁴ cm[superscript −2] , respectively . Rare -earth aluminate films , RAlO₃ , with R = Ce , Pr , Nd , Sm , Eu , Gd , and Tb , were also grown on STO . Conducting interfaces were found for R = Pr , Nd and Gd , and the results indicate that for R [does not equal] La the magnetic nature of the R³+ ion causes increased scattering with decreasing temperature that is modeled by the Kondo effect . Epitaxial strain between the polar RAlO₃ films and STO appears to play a crucial role in the transport properties of the metallic interface , where a decrease in the R³+ ion size causes an increase in sheet resistance and an increase in the onset temperatures for increased scattering . |