Electronic structure and thermodynamic stability of double-layeredSrTiO3(001)surfaces:Ab initiosimulations

Abstract

Using the B3PW hybrid exchange-correlation functional within density-functional theory and employing Gaussian-type basis sets, we calculated the atomic and electronic structures and thermodynamic stability of three double-layered ͑DL͒ SrTiO 3 ͑001͒ surfaces: ͑i͒ SrO-terminated, ͑ii͒ TiO 2 -terminated, and ͑iii͒ ͑2 ϫ 1͒ reconstruction of TiO 2 -terminated SrTiO 3 ͑001͒ recently suggested by Erdman et al. ͓Nature ͑London͒ 419, 55 ͑2002͔͒. A thermodynamic stability diagram obtained from first-principles calculations shows that regular TiO 2 -and SrO-terminated surfaces are the most stable. The stability regions of ͑2 ϫ 1͒ DL TiO 2 -and DL SrO-terminated surfaces lie beyond the precipitation lines of SrO and TiO 2 compounds and thus are less stable with respect to regular SrTiO 3 ͑001͒ surfaces. Analysis of the stability diagram suggests that Sr precipitation on SrTiO 3 surface never occurs. Our simulations show a substantial increase of Ti-O covalency on the DL surfaces as compared to the regular surfaces, which are themselves more covalent than the crystalline bulk. The implications of our calculated results for recent experimental observations are discussed.

Atomic and electronic structures of single-layer FeSe on SrTiO3(001): The role of oxygen deficiency

“…Even though a number of reconstructions have been observed on the SrTiO 3 (001) surface [24][25][26], we focused on the so-called double-layer-TiO 2 (2×1) surfaces [27,28] because other more complex surfaces are not compatible with the (2×1) reconstruction under study here. It has been found that, on the double-layer-TiO 2 (2×1) surface, the role of O vacancy is the same as that in the missingrow structure described above.…”

Oxygen adatoms at SrTiO3(001): A density-functional theory study

“…Identified as the only equilibrium surface structures 13,14,15 , the regular TiO 2 -and SrOterminations illustrated in Fig. 1 form a natural basis for our fundamental study addressing the energetics and electronic structure of O adatoms at cubic SrTiO 3 (001).…”

Method for defect stability diagram fromab initiocalculations: A case study of SrTiO3

“…This shows the extensive hybridization between the 3d-e g orbitals of the NN Ti and the two electrons localized at the vacant anionic site. 49,50 A singly and doubly charged oxygen vacancy is formed by removing one and two electrons, respectively, along with an oxygen atom from the defect free system. The local lattice near the vacancy in case of charged computation cells show greater distortions than a neutral cell.…”