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

P. Jaiban: M.‑H. Lu, T. Eknapakul, S. Chaiyachad, S. H. Yao, N. Pisitpipathsin, M. Unruan, S. Siriroj, R.‑H. He, S.‑K. Mo, A. Watcharapasorn, R. Yimnirun, Y. Tokura, Z.‑X. Shen, H.Y. Hwang, S. Maensiri & W. Meevasana; Scientific Reports, 10/08/20.

Additional Authors: M.‑H. Lu, T. Eknapakul, S. Chaiyachad, S. H. Yao, N. Pisitpipathsin, M. Unruan, S. Siriroj, R.‑H. He, S.‑K. Mo, A. Watcharapasorn, R. Yimnirun, Y. Tokura, Z.‑X. Shen, H.Y. Hwang, S. Maensiri & W. Meevasana

Abstract:

The discovery of a two-dimensional electron gas (2DEG) at the LaAlO3/SrTiO3 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 KTaO3BaTiO3 (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.