  The nature of the pseudogap in high transition temperature (high-Tc)
superconducting cuprates has been a major issue in condensed matter physics. It
is still unclear whether the high-Tc superconductivity can be universally
associated with the pseudogap formation. Here we provide direct evidence of the
existence of the pseudogap phase via angle-resolved photoemission spectroscopy
in another family of high-Tc superconductor, iron-pnictides. Our results reveal
a composition dependent pseudogap formation in the multi-band electronic
structure of BaFe2(As1-xPx)2. The pseudogap develops well above the
magnetostructural transition for low x, persists above the nonmagnetic
superconducting dome for optimal x and is destroyed for x ~ 0.6, thus showing a
notable similarity with cuprates. In addition, the pseudogap formation is
accompanied by inequivalent energy shifts in xz/yz orbitals of iron atoms,
indicative of a peculiar iron orbital ordering which breaks the four-fold
rotational symmetry.
