TY  - JOUR
AU  - Rubano, Andrea
AU  - De Luca, Gabriele
AU  - Schubert, Jürgen
AU  - Wang, Zhe
AU  - Zhu, Shaobo
AU  - Schlom, Darrell G.
AU  - Marrucci, Lorenzo
AU  - Paparo, Domenico
TI  - Polar asymmetry of La(1−δ)Al(1+δ)O3/SrTiO3 heterostructures probed by optical second harmonic generation
JO  - Applied physics letters
VL  - 107
IS  - 10
SN  - 1077-3118
CY  - Melville, NY
PB  - American Inst. of Physics
M1  - FZJ-2015-05625
SP  - 101603 -
PY  - 2015
AB  - By combining transport measurements and optical second harmonic generation, we have investigated heterostructures formed between crystalline thin films of LaAlO3, with varyingstoichiometry and TiO2-terminated SrTiO3(001) substrates. Optical second harmonic generationdirectly probes the polarity of these heterostructures, thus complementing the transport data. Thestoichiometry and the growth temperature are found to be critical parameters for controlling boththe interfacial conductivity and the heterostructure polarity. In agreement with the previous work,all of the samples display an insulator-to-metal transition in the Al-reach region, with the conductivityfirst increasing and then saturating at the highest Al/La ratios. The second harmonic signalalso increases as a function of the Al/La ratio, but, at the highest growth temperature, it does notsaturate. This unusual behavior is consistent with the formation of an ordered structure of defectdipoles in the LaAlO3 film caused by the off-centering of excess Al atoms in agreement with thetheory.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000361640200013
DO  - DOI:10.1063/1.4930881
UR  - https://juser.fz-juelich.de/record/230898
ER  -