  The recently discovered Fe-based superconductor (FeBS) LaFe2As2 seems to
break away from an established pattern that doping FeBS beyond 0.2e/Fe destroys
superconductivity. LaFe2As2 has an apparent doping of 0.5e, yet superconducts
at 12.1 K. Its Fermi surface bears no visual resemblance with the canonical
FeBS Fermiology. It also exhibits two phases, none magnetic and only one
superconducting. We show that the difference between them has nonetheless
magnetic origin, the one featuring disordered moments, and the other locally
nonmagnetic. We find that La there assumes an unusual valence of +2.6 to +2.7,
so that the effective doping is reduced to 0.30-0.35e. A closer look reveals
the same key elements: hole Fermi surfaces near Gamma-Z and electron ones near
the X-P lines, with the corresponding peak in susceptibility, and a strong
tendency to stripe magnetism. The physics of LaFe2As2 is thus more similar to
the FeBS paradigm than hitherto appreciated.
