Investigation of the Orbital Moment on the Fe Impurities in Iron-Based Superconductor

Our previous study show that the orbital exchange process induced by large orbital magnetic moment can lead to quantum anomalous vortices, which may further support robust Majorana zero-energy modes together with the topologically nontrivial surface states. In the present study, by applying LDA+Gutzwiller method we have systematically studied the value of the orbital magnetic moment as the function of the height between the Fe impurity and the surface of superconducting Fe(Te,Se). The local Coulomb Interaction between the electrons on the Fe impurities has been treated carefully by the rotational invariant Gutzwiller method with the variational parameters corresponding to the the most generic situation. Our results show the orbital contribution to the magnetic moment is always sizeable in this system and can be strongly affected by the impurity height.