Landau quantization and spin polarization of cold magnetized quark matter * *Support from the National Natural Science Foundation of China (11875181, 11875052, 11947098, 12005005, 61973109), the Hunan Provincial Natural Science Foundation of China (2021JJ40188), the Scientific Research Fund of Hunan Provincial Education Department of China (19C0772), the Scientific Research Fund of Hunan University of Science and Technology (E52059), and the

Abstract

The magnetic field and density behaviors of various thermodynamic quantities of strange quark matter under compact star conditions are investigated in the framework of the thermodynamically self-consistent quasiparticle model. For individual species, a larger number density leads to a larger magnetic field strength threshold that aligns all particles parallel or antiparallel to the magnetic field. Accordingly, in contrast to the finite baryon density effect which reduces the spin polarization of magnetized strange quark matter, the magnetic field effect leads to an enhancement of it. We also compute the sound velocity as a function of the baryon density and find the sound velocity shows an obvious oscillation with increasing density. Except for the oscillation, the sound velocity grows with increasing density, similar to the zero-magnetic field case, and approaches the conformal limit at high densities from below.