Mechanisms of charge transfer and redistribution in LaAlO3/SrTiO3 revealed by high-energy optical conductivity

被引：74

作者：

Asmara, T. C. ^{[1
,2
,3
]}

Annadi, A. ^{[1
,2
]}

Santoso, I. ^{[1
,2
,3
]}

Gogoi, P. K. ^{[1
,2
,3
]}

Kotlov, A. ^{[4
]}

Omer, H. M. ^{[3
]}

Motapothula, M. ^{[1
,2
,5
]}

Breese, M. B. H. ^{[2
,3
,5
]}

Ruebhausen, M. ^{[1
,6
,7
]}

Venkatesan, T. ^{[1
,2
,8
]}

Ariando ^{[1
,2
]}

Rusydi, A. ^{[1
,2
,3
]}

机构：

[1] Natl Univ Singapore, NUSNNI NanoCore, Singapore 117411, Singapore

[2] Natl Univ Singapore, Dept Phys, Singapore 117576, Singapore

[3] Natl Univ Singapore, Singapore Synchrotron Light Source, Singapore 117603, Singapore

[4] DESY, Hamburger Synchrotronstrahlungslab HASYLAB, D-22603 Hamburg, Germany

[5] Natl Univ Singapore, Ctr Ion Beam Applicat, Dept Phys, Singapore 117542, Singapore

[6] Univ Hamburg, Inst Angew Phys, D-20355 Hamburg, Germany

[7] Ctr Free Electron Laser Sci CFEL, D-22607 Hamburg, Germany

[8] Natl Univ Singapore, Dept Elect & Comp Engn, Singapore 117583, Singapore

来源：

NATURE COMMUNICATIONS | 2014年 / 5卷

基金：

新加坡国家研究基金会;

关键词：

SPECTRAL-WEIGHT; INTERFACES; OXIDE; SUPERCONDUCTIVITY; COEXISTENCE; SURFACES; LAALO3; SRTIO3;

D O I：

10.1038/ncomms4663

中图分类号：

O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];

学科分类号：

07 ; 0710 ; 09 ;

摘要：

In condensed matter physics the quasi two-dimensional electron gas at the interface of two different insulators, polar LaAlO3 on nonpolar SrTiO3 (LaAlO3/SrTiO3) is a spectacular and surprising observation. This phenomenon is LaAlO3 film thickness dependent and may be explained by the polarization catastrophe model, in which a charge transfer of 0.5e(-)from the LaAlO3 film into the LaAlO3/SrTiO3 interface is expected. Here we show that in conducting samples (>= 4 unit cells of LaAlO3) there is indeed a similar to 0.5e(-)transfer from LaAlO3 into the LaAlO3/SrTiO3 interface by studying the optical conductivity in a broad energy range (0.5-35 eV). Surprisingly, in insulating samples (<= 3 unit cells of LaAlO3) a redistribution of charges within the polar LaAlO3 sublayers (from AlO2 to LaO) as large as similar to 0.5e(-)is observed, with no charge transfer into the interface. Hence, our results reveal the different mechanisms for the polarization catastrophe compensation in insulating and conducting LaAlO3/SrTiO3 interfaces.

引用

页数：10

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