Speaker
Description
Origin of the strong magnetic field observed in compact stars has been an interesting issue. If nuclear matter favors spin polarization, it gives a possible origin of the magnetic field. However, any realistic calculation has not given positive results. We discuss some microscopic origin of the magnetic field in dense quark matter. We consider here two types of chiral transitions, dual chiral density wave (DCDW) phase and tensor condensate, both of which lead to spontaneous magnetization. After presenting some specific features of both phases, we discuss their magnetic properties. Different from the non-relativistic matter, magnetization is not simply proportional to spin polarization in quark matter. We carefully evaluate the thermodynamic potential under the external magnetic field, from which we can derive magnetization and magnetic susceptibility. Finally, we can see such spontaneous magnetization produces a sufficiently strong magnetic field of $O(10^{16})$ G on the surface of compact stars, which may be comparable with the observation of magnetars.