  Nuclear halo structure and restoration of relativistic symmetry are studied
within the framework of the relativistic Hartree-Fock-Bogoliubov (RHFB) theory.
Giant halos as well as ordinary ones are found in Cerium isotopes close to the
neutron drip line. Bridged by T=0 {channel}, the restoration of pseudo-spin
symmetry (PSS) plays an essential role in stabilizing the neutron halo
structures. The Fock terms, especially the $\rho$-tensor couplings, not only
play significant role in the PSS restoration but also present substantial
contributions to the T=0 {channel}, from which is well demonstrated the
necessity of Fock terms.
