  Spontaneous magnetization and magnetic susceptibility originated from the
pseudovector-type four-point interaction between quarks are calculated in quark
matter with zero temperature and finite quark chemical potential by using the
two-flavor Nambu-Jona-Lasinio model. It is shown that both the chiral
condensate and spin polarized condensate coexist in a narrow region of the
quark chemical potential. And then, it is also shown that, in this narrow
region, the spontaneous magnetization appears. Also, the magnetic
susceptibility due to quarks with the positive energy is evaluated in the spin
polarized phase.
