Spin polarization on Fermi surfaces of metals by the KKR method

With the implementation of a relativistic Korringa-Kohn-Rostoker Green's function and band-structure method, we analyze the spin-expectation value of the electron states on the Fermi surface of nonmagnetic as well as magnetic metals. It is shown that for relatively light elements such as Cu the spin states are well defined. A separation of all electron states to ``up'' and ``down'' spin-polarized states can be done even in the case of quite heavy but monovalent elements such as Au. In contrast, for heavy polyvalent metals such as Pt, the expectation value of the spin operator can be close to zero in large regions of the Fermi surface. In this case the nonrelativistic language of well-defined ``spin-up'' and ``spin-down'' states is not valid anymore. For magnetic materials, the relativistic Fermi surfaces change their topology with respect to the nonrelativistic majority and minority sheets because of spin-orbit driven avoided crossings of the bands. As a result, regions with vanishing spin polarization appear.