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- Schoofs, F., et al.
(author)
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Optimized transport properties of LaAlO3/SrTiO3 heterointerfaces by variation of pulsed laser fluence
- 2011
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In: Journal of Physics Condensed Matter. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 23:30
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Journal article (peer-reviewed)abstract
- We show the influence of pulsed laser deposition fluence on the transport properties of the LaAlO(3)/SrTiO(3) (LAO/STO) heterointerface. Structural characterization by x-ray diffraction and medium energy ion spectrometry enables us to deduce that the electronic behaviour is extremely sensitive to the stoichiometry of the LAO layer as well as the structural quality of the STO surface. An optimum balance of these two quantities is demonstrated for an intermediate laser fluence.
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- Aurino, Pier Paolo, 1985, et al.
(author)
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Reversible metal-insulator transition of Ar-irradiated LaAlO3/SrTiO3 interfaces
- 2015
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In: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 92:15
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Journal article (peer-reviewed)abstract
- The conducting state of a quasi-two-dimensional electron gas (q2DEG), formed at the heterointerface between the two wide-bandgap insulators LaAlO3 (LAO) and SrTiO3, can be made completely insulating by low-energy, 150-eV, Ar+ irradiation. The metallic behavior of the interface can be recovered by high-temperature oxygen annealing. The electrical transport properties of the recovered q2DEG are exactly the same as before the irradiation. Microstructural investigations confirm that the transition is not due to physical etching or crystal lattice distortion of the LAO film below its critical thickness. They also reveal a correlation between electrical state, LAO film surface amorphization, and argon ion implantation. The experimental results are in agreement with density functional theory calculations of Ar implantation and migration in the LAO film. This suggests that the metal-insulator transition may be caused by charge trapping in the defect amorphous layer created during the ion irradiation.
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- Boikov, Iouri, 1949, et al.
(author)
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Atomic rearrangements at the TiO2-terminated (001)SrTiO3 surface and growth of thin LaMnO3 films
- 2013
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In: Europhysics Letters. - : IOP Publishing. - 0295-5075 .- 1286-4854. ; 102:5
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Journal article (peer-reviewed)abstract
- SrTiO3 is commonly used as a substrate for growth of various oxide films. Different reconstructions at the SrTiO3 surface have been claimed. A question is whether these survive subsequent depositions of thin films and influence film properties. Medium energy ion scattering (MEIS) was used to probe structure and composition of the surface layer of a TiO2-terminated (001) SrTiO3 single-crystal substrate and 1-4 unit cell (u.c.) thick LaMnO3 epilayers. Aligned spectra indicate enrichment of Ti at the surface and a TiO2 double-layer (DL) configuration. The DL arrangement survives pulsed-laser deposition of LaMnO3 in a background of high oxygen pressure (5 x 10(-2) mbar) while it is destroyed at lower oxygen pressure (10(-4) mbar). Simulations of random MEIS spectra indicate substantial interdiffusion and La doping of the substrate surface but all interfaces are nevertheless insulating.
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- Boikov, Y. A., et al.
(author)
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Elastically strained and relaxed La0.67Ca0.33MnO3 films grown on lanthanum aluminate substrates with different orientations
- 2016
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In: Physics of the Solid State. - : Pleiades Publishing Ltd. - 1063-7834 .- 1090-6460. ; 58:12, s. 2560-2566
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Journal article (peer-reviewed)abstract
- Structure of 40-nm thick La0.67Ca0.33MnO3 (LCMO) films grown by laser evaporation on (001) and (110) LaAlO3 (LAO) substrates has been investigated using the methods of medium-energy ion scattering and X-ray diffraction. The grown manganite layers are under lateral biaxial compressive mechanical stresses. When (110)LAO wafers are used as the substrates, stresses relax to a great extent; the relaxation is accompanied by the formation of defects in a (3-4)-nm thick manganite-film interlayer adjacent to the LCMO-(110)LAO interface. When studying the structure of the grown layers, their electro- and magnetotransport parameters have been measured. The electroresistance of the LCMO films grown on the substrates of both types reached a maximum at temperature T (M) of about 250 K. At temperatures close to T (M) magnetoresistance of the LCMO/(110)LAO films exceeds that of the LCMO/(001)LAO films by 20-30%; however, the situation is inverse at low temperatures (T < 150 K). At T < T (M) , the magnetotransport in the grown manganite films significantly depends on the spin ordering in ferromagnetic domains, which increase with a decrease in temperature.
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