  We study the thermopower of diffusive Andreev interferometers, which are
hybrid loops with one normal-metal arm and one superconducting arm. The
thermopower oscillates as a function of the magnetic flux through the loop with
a fundamental period corresponding to one flux quantum $\Phi_0=h/2e$. Unlike
the electrical resistance oscillations and the thermal resistance oscillations,
which are always symmetric with respect to the magnetic field, the symmetry of
the thermopower oscillations can be either symmetric or antisymmetric depending
on the geometry of the sample. We also observe that the symmetry of the
thermopower oscillations is related to the distribution of the supercurrent
between the normal-metal/superconductor interfaces. We compare our experimental
results with recent theoretical work.
