  Magnetic catalysis of the chiral symmetry breaking and other magnetic
properties of the (2+1)-dimensional Gross--Neveu model are studied taking into
account the Zeeman interaction of spin-1/2 quasi-particles (electrons) with
tilted (with respect to a system plane) external magnetic field $\vec B=\vec
B_\perp+\vec B_\parallel$. The Zeeman interaction is proportional to magnetic
moment $\mu_B$ of electrons. For simplicity, temperature and chemical potential
are equal to zero throughout the paper. We compare in the framework of the
model the above mentioned phenomena both at $\mu_B=0$ and $\mu_B\ne 0$. It is
shown that at $\mu_B\ne 0$ the magnetic catalysis effect is drastically changed
in comparison with the $\mu_B= 0$ case. Namely, at $\mu_B\ne 0$ the chiral
symmetry, being spontaneously broken by $\vec B$ at subcritical coupling
constants, is always restored at $|\vec B|\to\infty$ (even at $\vec
B_\parallel=0$). Moreover, it is proved in this case that chiral symmetry can
be restored simply by tilting $\vec B$ to a system plane, and in the region $
B_\perp\to 0$ the de Haas -- van Alphen oscillations of the magnetization are
observed. At supercritical values of coupling constant we have found two
chirally non-invariant phases which respond differently on the action of $\vec
B$. The first (at rather small values of $|\vec B|$) is a diamagnetic phase, in
which there is an enhancement of chiral condensate, whereas the second is a
paramagnetic chirally broken phase. Numerical estimates show that phase
transitions described in the paper can be achieved at low enough laboratory
magnetic fields.
