Magnetism, spin texture, and in-gap states : atomic specialization at the surface of oxygen-deficient SrTiO3

Motivated by recent spin- and angular-resolved photoemission (SARPES) measurements of the two-dimensional electronic states confined near the (001) surface of oxygen-deficient SrTiO3, we explore their spin structure by means of ab initio density functional theory (DFT) calculations of slabs. Relativistic nonmagnetic DFT calculations display Rashba-like spin winding with a splitting of a few meV and when surface magnetism on the Ti ions is included, bands become spin-split with an energy difference ∼100 meV at the Γ point, consistent with SARPES findings. While magnetism tends to suppress the effects of the relativistic Rashba interaction, signatures of it are still clearly visible in terms of complex spin textures. Furthermore, we observe an atomic specialization phenomenon, namely, two types of electronic contributions: one is from Ti atoms neighboring the oxygen vacancies that acquire rather large magnetic moments and mostly create in-gap states; another comes from the partly polarized t2g itinerant electrons of Ti atoms lying further away from the oxygen vacancy, which form the two-dimensional electron system and are responsible for the Rashba spin winding and the spin splitting at the Fermi surface.

DDC Class

530: Physik

600: Technik

Funding Organisations

Deutsche Forschungsgemeinschaft (DFG)

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M. A., H. O. J., and R. V. gratefully acknowledge the Deutsche Forschungsgemeinschaft (DFG) for financial support through SFB/TR 49 and FOR 1346.
M. A. and R. V. were partially supported by the Kavli Institute for Theoretical Physics at the University of California, Santa Barbara under National Science Foundation Grant No. PHY11-25915.
A. F. S.-S. and M. G. acknowledge support from the Institut Universitaire de France and from the French National Research Agency (ANR) (Project LACUNES No. ANR-13-BS04-0006-01).

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To cite this version: Michaela Altmeyer, Harald O. Jeschke, Oliver Hijano-Cubelos, Cyril Martins, Frank Lechermann, Klaus Koepernik, Andrés F. Santander-Syro, Marcelo J. Rozenberg, Roser Valentí, and Marc Gabay. Magnetism, Spin Texture, and In-Gap States: Atomic Specialization
at the Surface of Oxygen-Deficient SrTiO3. Physical Review Letters, American Physical Society, 2019, 116 (15), pp. 157203

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PhysRevLett.116.157203.pdf

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Magnetism, spin texture, and in-gap states : atomic specialization at the surface of oxygen-deficient SrTiO3