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arXiv 2505.24809cond-mat.mtrl-sci
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外延LaFeO$_3$(001)薄膜在带隙以上激发下的超快电子动力学

Ultrafast electron dynamics upon above band-gap excitation in epitaxial LaFeO$_3$(001) thin films

Friederike Elisa Wührl, Antonia Rieche, Anne Oelschläger, Kathrin Dörr, Wolf Widdra

AI总结:

本研究利用2PPE和UV-UV泵浦-探测技术,揭示了外延LaFeO$_3$(001)薄膜带隙以上激发后的超快电子动力学,发现三个非占据态及导带底的双指数衰减路径。

摘要:

钙钛矿氧化物中的强电子关联引发了丰富且常出乎意料的电子现象。本研究对电荷转移绝缘体LaFeO$_3$(001)的外延薄膜进行了全面的表面科学研究。表征手段包括低能电子衍射(LEED)、高分辨率电子能量损失谱(HREELS)和光电子能谱。我们利用双光子光电子能谱(2PPE)绘制了占据态和非占据态。此外,通过紫外-紫外(UV-UV)泵浦-探测实验探测电子动力学,将电子从杂化的O~$2p$/Fe $3d$态激发至带隙以上的Fe少数自旋态。结果揭示了三个不同的非占据态,分别归属于Fe $t_{2g\downarrow}$、Fe $e_{g\downarrow}$和La $5d$轨道。值得注意的是,导带底表现出双指数衰减,时间常数分别为39\\,fs和1100\\,fs,表明存在两条独立的衰减路径。

英文摘要:

Strong electron correlations in perovskite oxides give rise to rich and often unexpected electronic phenomena. In this study, we present a comprehensive surface-science investigation of epitaxial thin films of the charge-transfer insulator LaFeO$_3$(001). The characterization includes low-energy electron diffraction (LEED), high-resolution electron energy loss spectroscopy (HREELS), and photoemission spectroscopy. We map both the occupied and unoccupied electronic states using two-photon photoemission (2PPE) spectroscopy. Furthermore, we probe electron dynamics through an ultraviolet-ultraviolet (UV-UV) pump-probe experiment, exciting electrons from hybridized O~$2p$/Fe $3d$ states to Fe minority-spin states above the band gap. Our results reveal three distinct unoccupied states, which we assign to Fe $t_{2g\downarrow}$, Fe $e_{g\downarrow}$, and La $5d$ orbitals. Notably, the conduction band minimum exhibits a biexponential decay with time constants of 39\,fs and 1100\,fs, suggesting the presence of two independent decay pathways.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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