  In this paper the dominant effect of electron inertia on the dynamics of
localized density excitations is studied in a quantum plasma in the presence of
electron spin effects. Using the quantum magnetohydrodynamics (QMHD) model
including electron tunneling and spin polarization phenomena, it is revealed
that the quantum effects such as plasma paramagnetism and diamagnetism play
inevitable role on soliton existence criteria in quantum plasmas. Furthermore,
it is shown that the magnetosonic localized density-excitation stability
depends strongly on the quantum system dimensionality. Two distinct region of
soliton stability is shown to exist depending on the value of the electron
effective mass, where, the soliton amplitude variation with respect to the
external magnetic field strength is quite opposite in these regions. Current
findings can be important in the study of dynamical nonlinear wave features in
dense laboratory or inertial-confined plasmas.
