Subband Structure of a Two-Dimensional Electron Gas Formed at the Polar Surface of the Strong Spin-Orbit Perovskite KTaO 3
Year: 2012
Type: article
Abstract: We demonstrate the formation of a two-dimensional electron gas (2DEG) at the (100) surface of the $5d$ transition-metal oxide ${\mathrm{KTaO}}_{3}$. From angle-resolved photoemission, we find that quantum confinement lifts the orbital degeneracy of the bulk band structure and leads to a 2DEG composed of ladders of subband states of both light and heavy carriers. Despite the strong spin-orbit coupling, our measurements provide a direct upper bound for the potential Rashba spin splitting of only $\ensuremath{\Delta}{k}_{\ensuremath{\parallel}}\ensuremath{\sim}0.02\text{ }\text{ }{\AA{}}^{\ensuremath{-}1}$ at the Fermi level. The polar nature of the ${\mathrm{KTaO}}_{3}(100)$ surface appears to help mediate the formation of the 2DEG as compared to nonpolar ${\mathrm{SrTiO}}_{3}(100)$.
Source: Physical Review Letters
Institutions: University of St Andrews, Lawrence Berkeley National Laboratory, Advanced Light Source, Synchrotron Light Research Institute, Suranaree University of Technology, Japan Science and Technology Agency, The University of Tokyo, SLAC National Accelerator Laboratory, Stanford University, RIKEN, RIKEN Advanced Science Institute, Thailand Center of Excellence in Physics
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2132673045