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    Polarization screening and induced carrier density at the interface of LaAlO3_3 overlayer on SrTiO3_3 (001)

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    We investigate the role of lattice polarization in determination of induced carrier density at the nn-type interface of LaAlO3_3 overlayer on SrTiO3_3 (001) by carrying out density-functional-theory calculations. When no oxygen vacancy or defect is present, the magnitude of polarization screening in the LaAlO3_3 layers is found to be correlated with the carrier charge induced at the interface. For the interfaces with a few LaAlO3_3 layers, the induced charge carrier is compensated by the electrostatic screening and consequently its density remains far less than 0.5 electrons per unit cell.Comment: 4 pages, 4 figure

    Special Session on Industry 4.0

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    Applications of degree estimate for subalgebras

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    Let KK be a field of positive characteristic and KK be the free algebra of rank two over KK. Based on the degree estimate done by Y.-C. Li and J.-T. Yu, we extend the results of S.J. Gong and J.T. Yu's results: (1) An element p(x,y)∈Kp(x,y)\in K is a test element if and only if p(x,y)p(x,y) does not belong to any proper retract of KK; (2) Every endomorphism preserving the automorphic orbit of a nonconstant element of KK is an automorphism; (3) If there exists some injective endomorphism Ο•\phi of KK such that Ο•(p(x,y))=x\phi(p(x,y))=x where p(x,y)∈Kp(x,y)\in K, then p(x,y)p(x,y) is a coordinate. And we reprove that all the automorphisms of KK are tame. Moreover, we also give counterexamples for two conjectures established by Leonid Makar-Limanov, V. Drensky and J.-T. Yu in the positive characteristic case.Comment: 12 page
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