  The performance of Heusler based magnetoresistive multilayer devices depends
crucially on the spin polarization and thus on the structural details of the
involved surfaces. Using low energy electron diffraction (LEED), one can
non-destructively distinguish between important surface terminations of Co2XY
full-Heusler alloys. We present an analysis of the LEED patterns of the Y-Z
,the vacancy-Z, the Co and the disordered B2 and A2 terminations. As an
example, we show that the surface geometries of bulk L21 ordered Co2MnSi and
bulk B2 disordered Co2Cr0.6Fe0.4Al can be determined by comparing the
experimental LEED patterns with the presented reference patterns.
