  We observe anisotropic Hanle lineshape with unequal in-plane and out-of-plane
non-local signals for spin precession measurements carried out on lateral
metallic spin valves with transparent interfaces. The conventional
interpretation for this anisotropy corresponds to unequal spin relaxation times
for in-plane and out-of-plane spin orientations as for the case of 2D materials
like graphene, but it is unexpected in a polycrystalline metallic channel.
Systematic measurements as a function of temperature and channel length,
combined with both analytical and numerical thermoelectric transport models,
demonstrate that the anisotropy in the Hanle lineshape is magneto-thermal in
origin, caused by the anisotropic modulation of the Peltier and Seebeck
coefficients of the ferromagnetic electrodes. Our results call for the
consideration of such magnetothermoelectric effects in the study of anisotropic
spin relaxation.
