2015/06/17 by Pranjal Kumar Gogoi, Lorenzo Sponza, Gogoi, Pranjal Kumar +19
Materials Science · Physics and Astronomy · #Electronic and Structural Properties of Oxides #FOS: Physical sciences #Magnetic and transport properties of perovskites and related materials #Physics of Superconductivity and Magnetism #Strongly Correlated Electrons (cond-mat.str-el)
paper · pdf · doi:10.48550/arxiv.1506.05262
openalex publication_date 2015/06/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Electron-electron (e-e) and electron-hole (e-h) interactions are often associated with many exotic phenomena in correlated electron systems. Here, we report an observation of anomalous excitons at 3.75 , 4.67 and 6.11 eV at 4.2 K in bulk-SrTiO3. Fully supported by ab initio GW Bethe-Salpeter equation calculations, these excitons are due to surprisingly strong e-h and e-e interactions with different characters: 4.67 and 6.11 eV are resonant excitons and 3.75 eV is a bound Wannier-like exciton with an unexpectedly higher level of delocalization. Measurements and calculations on SrTi1-xNbxO3 for 0.0001≤x≤0.005 further show that energy and spectral-weight of the excitonic peaks vary as a function of electron doping (x) and temperature, which are attributed to screening effects. Our results show the importance of e-h and e-e interactions yielding to anomalous excitons and thus bring out a new fundamental perspective in SrTiO3.