Subband structure of a two-dimensional electron gas formed at the polar surface of the strong spin-orbit perovskite KTaO3
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We demonstrate the formation of a two-dimensional electron gas (2DEG) at the (100) surface of the 5d transition-metal oxide KTaO3. 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 Delta k(parallel to) similar to 0.02 angstrom(-1) at the Fermi level. The polar nature of the KTaO3(100) surface appears to help mediate the formation of the 2DEG as compared to nonpolar SrTiO3(100).
King , P D C , He , R H , Eknapakul , T , Buaphet , P , Mo , S-K , Kaneko , Y , Harashima , S , Hikita , Y , Bahramy , M S , Bell , C , Hussain , Z , Tokura , Y , Shen , Z-X , Hwang , H Y , Baumberger , F & Meevasana , W 2012 , ' Subband structure of a two-dimensional electron gas formed at the polar surface of the strong spin-orbit perovskite KTaO 3 ' Physical Review Letters , vol 108 , no. 11 , 117602 . DOI: 10.1103/PhysRevLett.108.117602
Physical Review Letters
© 2012 American Physical Society
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