Spectral weight reduction of two-dimensional electron gases at oxide surfaces across the ferroelectric transition

• Published in: Scientific reports 2020-10, Vol.10 (1), p.16834-16834, Article 16834
• Main Authors: Jaiban, P., Lu, M.-H., Eknapakul, T., Chaiyachad, S., Yao, S. H., Pisitpipathsin, N., Unruan, M., Siriroj, S., He, R.-H., Mo, S.-K., Watcharapasorn, A., Yimnirun, R., Tokura, Y., Shen, Z.-X., Hwang, H. Y., Maensiri, S., Meevasana, W.
• Format: Article
• Language: English
• Subjects: 639/766/119/2795; 639/766/119/995; 639/766/119/996; electronic properties and materials; ferroelectrics and multiferroics; Humanities and Social Sciences; MATERIALS SCIENCE; multidisciplinary; phase transitions and critical phenomena; Science; Science (multidisciplinary)
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-020-73657-1

The discovery of a two-dimensional electron gas (2DEG) at the LaAlO 3 / SrTiO 3 interface has set a new platform for all-oxide electronics which could potentially exhibit the interplay among charge, spin, orbital, superconductivity, ferromagnetism and ferroelectricity. In this work, by using angle-resolved photoemission spectroscopy and conductivity measurement, we found the reduction of 2DEGs and the changes of the conductivity nature of some ferroelectric oxides including insulating Nb-lightly-substituted KTaO 3 , BaTiO 3 (BTO) and (Ca,Zr)-doped BTO across paraelectric-ferroelectric transition. We propose that these behaviours could be due to the increase of space-charge screening potential at the 2DEG/ferroelectric regions which is a result of the realignment of ferroelectric polarisation upon light irradiation. This finding suggests an opportunity for controlling the 2DEG at a bare oxide surface (instead of interfacial system) by using both light and ferroelectricity.