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Department of Physics and Astronomy, University of British Columbia
412_2355 East Mall, Vancouver, BC V6T 1Z4, Canadav|JÚà®_»¨ÌweÚiÙÈé¨¿ÌÚjÉ¨¯éEÊÍC\¬·éÂXÌ¨¿ÆÍÙÈÁ½«¿ð

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æÁÄ SrTiO3/LaAlO3 EÊÌdqóÔðÏªµæ¤Æ¢¤ÝÉÂ¢ÄÐî·éBVµ¢¬ÊÆµÄC±ÌnÉ¨¯édC`±ðà½ç·dqIÄ\¬ÌlqâC2 íÞÌEÊÌ«¿Ìá¢ª¾ç©ÉÈÁ½BÅãÉC¡ãÌW]ÉÂ¢Ä
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LVO)5)ÈÇÉ©çêé LaO/TiO2/SrO EÊÉ¨¯éà®
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Fig. 1

Two possible interfaces between LaAlO3 and SrTiO3 in the(001) orientation1). (a) Schematic of the LaO/TiO2/SrO in­
terface, showing the composition of each layer and the ioniccharge state of each layer. (b) Schematic of the SrO/AlO2/
LaO interface.

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70  úËõ March 2009 Vol.22 No.2
(C) 2009 The Japanese Society for Synchrotron Radiation ResearchgsbNX ¡ ¤Âî X üUÉæé SrTiO3/LaAlO3 EÊÌdqóÔÌÏªâ«ðÛµÄ¢é±Æª¦³ê½17_19) BSTO/LAO

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Fig. 2 X­ray reectivity and absorption spectra from the SrTiO3/
LaAlO3 superlattice. (a) Reectivity spectra measured at458.4 eV (Ti 2p on­resonance) and 455 eV (Ti 2p o­
resonance). (b) Ti 2p absorption spectra. (c) Schematic
view of the SrTiO3/LaAlO3 superlattice.

úËõ March 2009 Vol.22 No.2  71

Bragg s[Nð¦µÄ¢éBU®Í Ti 2p Ìñ¤ÂioresonancejÅ

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Ci003)Í­xªÉßÄ¬³¢Ö§s[NÆÈéBÖ§s[NÌ¶ÝÍC¶£24)ÅÌ LMO/SMO ´iqÌêÆ¯¶ÅéBLMO/SMO ´iqÅÍ(003)s[NÍ¤ÂÅÌÝÏª³ê½ªC¡ñÌ STO/LAO ´iqÅÍ¤ÂCñ¤ÂÌ¼ûÅÏª³êÄ¢éB±Ì·ÙÍCLMO/
SMO ´iqÉ¨¢ÄÍ LMO Æ SMO Å MnO2 Êª¤ÊÅé½ßCSrO/MnO2 /LaO Æ¢¤ 1 íÞÌEÊµ©¶Photon­energy dependence of the (002) and (003) peaks
near the Ti 2p (a) and O 1s (b) absorption edges. Top andmiddle panels show intensity maps of (002) and (003)
regions, respectively. Here bright parts correspond to highintensities. Bottom panels show the (002) and (003) peakheights together with the XAS spectra. (c) is the case of the
LMO/SMO superlattice near the O 1s absorption edge, as
described in Ref. 24). A top panel shows an intensity map ofthe (003) region, where red parts correspond to high intensi­
ties. A bottom panel shows the (001), (002) and (003) peakintensities together with the XAS spectrum.

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0 u |v(4)èCEÊÉq´Æl¦çêé(003)s[NÅÍC¼ÒÌêÜèÇ­È¢B±êÍEÊÉ¨¯é Ti 3d Æ O 2pvÍÌóÔÌdqIÄ\¬ªN±èC»êÉæèõwIÈ«¿±±ÅCZ Í´qÔCP Í Cauchy ÌålÏªð¦·BªÂXÌoNÌ¨¿ÆÍÙÈÁ½½ßÆl¦çêéB±Fig. 4 Í±Ìæ¤ÉµÄ¾çê½ d ÌlÆ®(1)ðp¢Ì±ÆÉæèCdqIÉ}sÈEÊÆ¢¤ÅÌ¼èªsKÅèC®(1)ÌÅ¼èµ½õwèª³µ­È¢±Æªª©éB±ÌÀ±ÊÌÝ©çÍC±êª_f¹âêÌæ¤Ègñ{¿IÈh´öÉæéÂ\«ÍÛèÅ«È¢ªCi002)s[NÉ¨¯éÀ±ÆvZÌæ¢êvð©éÆC\¢ÌâèÅÍÈ­dqIÄ\¬ð¦´·éæ¤ÅéBie)ð©éÆ La 3d zû[ÅÍ(003)s[NÉ¨¢ÄÀ±ÆvZÌêvªæ¢B±Ì±ÆÍEÊÉ¨¢Ä¶£30)Åñ¥³ê½æ¤È La ´qÌgUÌøÊª¬³¢±Æð¦µÄ¢éBÅãÉLæÌ½Ë¦ÌðÍðsÁ½B½wÉ¨¯é½Ë¦ÍCParratt ÌQ»®Ìû@31,32) ÉæÁÄvZ·é±ÆªÅ«éB±±ÅäXÍCFig. 5 Ì(g)É¦· 4 ÂÌFig. 4Peak­position analyses by considering the eects of refrac­tion (d). (a) (002) at the Ti 2p edge. (b) (003) at the Ti 2pedge. (c) (002) at the O 1s edge. (d) (003) at the O 1s edge.
(e) (003) at the La 3d edge.

Fig. 5fiA, B1, B2, Cjðl¦½Bf A ÅÍ·×ÄÌEÊªõwIÉ}siüÜ¦ d, b ª}ÉÏ»·éjÆµ½Bf C Í»Ì½ÎÉ·×ÄÌEÊªõwIÉ}s

Comparison of the reectivity spectra between experiment and calculation. (a) Ti 2p on­resonance. (b) Ti 2p o­
resonance. (c) O 1s on­resonance. (d) O 1s o­resonance. (e) La 3d on­resonance. (f) La 3d o­resonance. (g)Models of our superlattice samples.

úËõ March 2009 Vol.22 No.2  73Å È ­ CE Ê Å d, b Í STO, LAO Ì ½ Ï lð Æ é Æ µÍÏ³¹é±ÆÅCEÊÍ·×Ä n ^iLaO/TiO2/SrOj½B±Ì 2 ÂÌfÍCn ^EÊÆ p ^EÊÌá¢ðl

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 ÒÐî aBå÷ú{wpU»ï COÁÊ¤õ
Department of Physics and Astronomy,
University of British ColumbiaE­mail: wadatiphas.ubc.ca
êåFÅÌ¨wCÁÉõdqªõÉXüzûªõÉ¤Â X üUÉæé­ÖJÚà®_»¨ÌdqóÔÌ¤B
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2007N 3 åwåw@wn¤ÈmÛöC¹C2007N 4 æè»EB

Electronic structure of the SrTiO3/LaAlO3 interface
revealed by resonant soft x­ray scattering
Hiroki WADATIJSPS Postdoctoral Fellow for Research Abroad
Department of Physics and Astronomy, University of British Columbia
412_2355 East Mall, Vancouver, BC V6T 1Z4, Canada

Abstract Interfaces between transition­metal oxides often exhibit electronic properties that are absent in in­dividual bulk materials, and have been one of the most important issues in contemporary condensed­matterphysics. Here we introduce our recent resonant soft x­ray scattering studies of the electronic structures of
SrTiO3/LaAlO3 interfaces. We obtained evidence for electronic reconstruction of Ti 3d and O 2p states at theinterface, and concluded that the two types of interfaces in this system are quite dierent, leading to highly
asymmetric properties. We also show our future prospects related to this study.

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