  We present genuine bulk Ir 5d jeff states of layered perovskite iridates
obtained by hard-x-ray photoemission spectroscopy (HAXPES) with s- and
p-polarized lights. HAXPES spectra of Sr2IrO4 and Ba2IrO4 are well reproduced
by the quasi-particle densities of states calculated by the local density
approximation with dynamical mean-field theory (LDA+DMFT). It is demonstrated
that the insulating nature of the iridates is triggered by antiferromagnetic
correlation (Slater type) combined with electron correlation (Mott type). The
extremely-low-energy bulk-sensitive photoemission spectroscopy reveals "bad
metallic" states in the paramagnetic phase of the iridates, suggesting strongly
renormalized metallic states above the Neel temperature as predicted by the
LDA+DMFT.
