  Kagome superconductors AV3Sb5 (A = K, Rb, Cs) exhibit a characteristic
superconducting and charge-density wave (CDW) phase diagram upon carrier doping
and chemical substitution. However, the key electronic states responsible for
such a phase diagram have yet to be clarified. Here we report a systematic
micro-focused angle-resolved photoemission spectroscopy (ARPES) study of
Cs(V1-xCrx)3Sb5 as a function of Cr content x, where Cr substitution causes
monotonic reduction of superconducting and CDW transition temperatures. We
found that the V-derived bands forming saddle points at the M point and Dirac
nodes along high-symmetry cuts show an energy shift due to electron doping by
Cr substitution, whereas the Sb-derived electron band at the Gamma point
remains almost unchanged, signifying an orbital-selective band shift. We also
found that band doubling associated with the emergence of three-dimensional CDW
identified at x = 0 vanishes at x = 0.25, in line with the disappearance of
CDW. A comparison of band diagrams among Ti-, Nb-, and Cr-substituted
Cs(V1-xCrx)3Sb5 suggests the importance to simultaneously take into account the
two saddle points at the M point and their proximity to the Fermi energy, to
understand the complex phase diagram against carrier doping and chemical
pressure.
