  We studied the thermoelectric coefficients (Seebeck and thermal
conductance)of FeCo|MgO|FeCo(001) magnetic tunnel junctions (MTJs) from first
principles using a generalized Landauer-B\"{u}ttiker formalism.
FeCo|MgO|FeCo(001) MTJs usually yield smaller thermoelectric effects compared
with epitaxial Fe|MgO|Fe(001) MTJs. The (magneto-) Seebeck effect is sensitive
to the details of the FeCo$|$MgO interfaces. Interfacial oxygen vacancies (OVs)
can enhance the thermoelectric effects in MTJs greatly. We also compute angular
dependent Seebeck coefficients that provide more information about the
transport physics. We report large deviations from the Wiedemann-Franz law at
room temperature.
