Adiabatic renormalization of the stress-energy tensor for spin-1/2 fields

We review the adiabatic renormalization method for spin-1/2 fields in FLRW spacetimes, emphasizing its similarities and differences with the scalar case. With it, we obtain a generic expression for the renormalized expectation value of the stress-energy tensor and analyze its properties. We particularize this result to de Sitter and radiation-dominated universes, recovering in the second case the equations of cold matter for late times. (paper)