Various magnetic properties of amorphous Fe-Zr alloys have been invest
igated on the basis of the finite-temperature theory of amorphous magn
etic alloys. The numerical results explain the overall features of the
magnetization versus concentration curve and the magnetic phase diagr
am showing the spin glass, the ferromagnetism, and the paramagnetism,
including the re-entrant spin-glass behavior in the Fe-rich region. It
is verified by various analyses that the spin glass is caused by the
nonlinear magnetic couplings and the fluctuations of the amplitudes of
local moments due to structural disorder, while the ferromagnetism is
stabilized by the decrease in the average coordination number of Fe a
toms due to atomic size effects. Broad distributions of the local magn
etic moments are found in both spin-glass and ferromagnetic states in
the Fe-rich region. Their concentrations and temperature dependences a
re elucidated on the basis of the electronic structure and nonlinear m
agnetic couplings. Calculated high-field susceptibilities explain the
anomaly around the re-entrant spin-glass region. Calculated effective
Bohr magneton numbers predict a minimum around 35 at% Fe. The effects
of atomic short-range order on the magnetic phase diagram are also inv
estigated. It is found that the ferromagnetism disappears in the whole
concentration when the probability of finding an Fe atom at the neigh
boring site of an Fe atom is larger than 0.8.