Photoemission from buried interfaces in SrTiO3/LaTiO3 superlattices
Photoemission from buried interfaces in SrTiO3/LaTiO3 superlattices
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DOI：
10.1103/physrevlett.97.057601
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发表时间：
2006-08-04
影响因子：
8.6
通讯作者：
Millis, A. J.
中科院分区：
文献类型：
--
作者：
Takizawa, M.;Wadati, H.;Millis, A. J.
我们测量了SrTiO_3/LaTiO_3超晶格的光电子能谱，其中最上层的SrTiO_3层的厚度是可变的。在化学突变的SrTiO 3/LaTiO 3界面处观察到有限的相干光谱权重，具有清晰的费米截止，表明在Mott绝缘体LaTiO 3和能带绝缘体SrTiO 3之间的界面处发生“电子重构”。对于SrTiO 3/LaTiO 3界面在高温（类似于1000摄氏度）下退火，这导致Sr/La原子相互扩散，从而形成La 1-xSrxTiO 3-like材料，发现非相干部分的强度显著降低，而具有尖锐费米截止的相干部分由于电荷的扩散而增强。层动力平均场理论计算很好地再现了这些重要的实验特征。
We have measured photoemission spectra of SrTiO3/LaTiO3 superlattices with a topmost SrTiO3 layer of variable thickness. A finite coherent spectral weight with a clear Fermi cutoff was observed at chemically abrupt SrTiO3/LaTiO3 interfaces, indicating that an "electronic reconstruction" occurs at the interface between the Mott insulator LaTiO3 and the band insulator SrTiO3. For SrTiO3/LaTiO3 interfaces annealed at high temperatures (similar to 1000 degrees C), which leads to Sr/La atomic interdiffusion and hence to the formation of La1-xSrxTiO3-like material, the intensity of the incoherent part was found to be dramatically reduced whereas the coherent part with a sharp Fermi cutoff was enhanced due to the spread of charge. These important experimental features are well reproduced by layer dynamical-mean-field-theory calculation.