Surface of strontium titanate.
We report the first complete determination, using surface x-ray diffraction, of the surface structure of TiO2-terminated SrTiO3(001), both at room temperature in vacuum, and also hot, under typical conditions used for thin film growth. The cold structure consists of a mixture of a (1x1) relaxation and (2x1) and (2x2) reconstructions. The latter disappear over several minutes upon heating. The structures are best modeled by a TiO2-rich surface similar to that proposed by Erdman et al. [Nature (London) 419, 55 (2002).10.1038/nature01010]. Both reconstructions have been shown by density functional theory to be energetically favorable. The calculated (1x1) surface energy is higher, indicating that it may be a disordered mixture of the reconstructions. Atomic displacements are significant down to three unit cells, which may have important implications on possible surface ferroelectric phenomena in SrTiO3.
Herger
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R
Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
Willmott
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PR
Bunk
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O
Schlepütz
C M
CM
Patterson
B D
BD
Delley
B
B