Deformed ground state of $^{ 32}$Mg is investigated using the axially deformed relativistic Hartree-Fock-Bogoliubov (D-RHFB) model with the effective Lagrangian PKA1, which provides coincident description with the experimental measurements. It is illustrated that obvious breaking of the pseudo-spin symmetry (PSS) given by PKA1, being consistent with the experimental observation in nearby isotone $^{ 40}$Ca, is crucial for describing correctly the deformed ground state by producing unique shape evolution of neutron orbit $1/2_4^+$ in $^{ 32}$Mg. The PSS breaking is essentially determined by characteristic in-medium balance between nuclear attractions and repulsions that is manifested as unparalleled density dependent behaviors for coupling strengths $g_\sigma$ and $g_\omega$ in dominant $\sigma$-scalar and $\omega$-vector channels.
Categories: nucl-th