  We present x-ray reflectivity, x-ray diffraction and atomic force microscopy
measurements of single crystal SrTiO3 taken as a function of temperature. We
found a rumpling transformation of the SrTiO3 surface after cooling the sample
below ~105 K. The rumpling transformation is correlated with the cubic to
tetragonal phase transformation that occurs at the same temperature. The
rumpling transformation is reversible.
