  The in-medium masses of the lowest S-wave charmonium states (vector meson,
$J/\psi$ and pseudoscalar meson, $\eta_c$) and P-wave charmonium states
(scalar, $\chi_{c0}$ and axialvector $\chi_{c1}$) are investigated in
magnetized nuclear matter, within the framework of QCD sum rule approach. These
are computed from the medium modifications of the scalar as well as twist--2
gluon condensates, obtained from the medium modifications of a scalar dilaton
field, within a chiral effective model. The effects of the magnetic field,
isospin asymmetry and density on the masses of these charmonium states have
been investigated. The modifications of the masses of the P-wave charmonium
states ($\chi_{c0}$ and $\chi_{c1}$) are observed to be much larger as compared
to those of the S-wave states, $J/\psi$ and $\eta_c$ within the QCD sum rule
approach. The effects of the coupling of the spin with the magnetic field are
also investigated in the present work, which result in the mixing of the spin
zero charmonium state with the longitudinal component of the vector meson. This
leads to an increase (drop) in mass of the longitudinal $J/\psi$ ($\eta_c$) for
the S-wave states. The effects of the spin-magnetic field interactions are
observed to be dominant at high magnetic fields.
