  The complete quasi-particle spectrum of a magnetized electromagnetic plasma
is systematically explored at zero and nonzero temperatures. To this purpose,
the general structure of the one-loop corrected propagator of magnetized
fermions is determined, and the dispersion relations arising from the pole of
this propagator are numerically solved. It turns out that in the lowest Landau
level, where only one spin direction is allowed, the spectrum consists of one
positively (negatively) charged fermionic mode with positive (negative) spin.
In contrast, in higher Landau levels, as an indirect consequence of the double
spin degeneracy of fermions, the spectrum consists of two massless collective
modes with left- and right-chiralities. The mechanism through which these new
collective excitations are created in a uniform magnetic field is similar to
the production mechanism of dynamical holes (plasminos) at finite temperature
and zero magnetic fields. Whereas cold magnetized plasminos appear for moderate
magnetic fields and for all positive momenta of propagating fermions, hot
magnetized plasminos appear only in the limit of weak magnetic fields and soft
momenta.
