Photothermal methods were used to monitor thermal effects related to magnetoresistance of epitaxial magnetic metallic multilayers, in a direction perpendicular to the layers, as a function of the applied magnetic field. Photothermal signal changes induced by thermal conductivity variations were modeled in order to determine the suitable experimental conditions according to the technique used. Both photothermal microscopy and mirage detection were successfully applied to such measurements. For the sample studied here, a magneto induced perpendicular conductivity variation of ∼6&percent; was determined. ©1997 American Institute of Physics.