  The local electronic and atomic structures of the high-quality single crystal
of SrFeO3-{delta} ({delta}~0.19) were studied using temperature-dependent x-ray
absorption and valence-band photoemission spectroscopy (VB-PES) to investigate
the origin of anisotropic resistivity in the ab-plane and along the c-axis
close to the region of thermal hysteresis (near temperature for susceptibility
maximum, Tm~78 K). All experiments herein were conducted during warming and
cooling processes. The Fe L3,2-edge X-ray linear dichrois results show that
during cooling from room temperature to below the transition temperature, the
unoccupied Fe 3d eg states remain in persistently out-of-plane 3d3z2-r2
orbitals. In contrast, in the warming process below the transition temperature,
they change from 3d3z2-r2 to in-plane 3dx2-y2 orbitals. The nearest-neighbor
(NN) Fe-O bond lengths also exhibit anisotropic behavior in the ab-plane and
along the c-axis below Tm. The anisotropic NN Fe-O bond lengths and
Debye-Waller factors stabilize the in-plane Fe 3dx2-y2 and out-of-plane
3d3z2-r2 orbitals during warming and cooling, respectively. Additionally, a
VB-PES study further confirms that a relative band gap opens at low temperature
in both the ab-plane and along the c-axis, providing the clear evidence of the
charge-density-wave nature of SrFeO3-{delta} ({delta}~ 0.19) single crystal.
