We have investigated the dependence of the giant magnetoresistance (GMR) effect, the coercivity, the coupling field, and the resistivity on film deposition at low‐substrate temperatures (150 K) in spin valve multilayers of the general type: FeMn/Ni 80 Fe 20 /Co/Cu/Co/Ni 80 Fe 20 /glass. Low substrate temperatures tend to suppress both thermally activated surface diffusion of deposited atoms and interdiffusion at interfaces, which often occur during thin‐film deposition at room temperature. We find significant increases in the GMR, significant reductions in the magnetic coupling across the Cu layer, slight reductions in the coercivity of the unpinned film, and slight reductions in the resistivity depending on which parts of the multilayer are deposited at low temperature. When the entire film is deposited at 150 K we obtain a GMR of 8.8% at a coercivity of less than 0.5 mT (5 Oe). © 1996 American Institute of Physics.