  Using wave function matching approach and employing the Landauer-Buttiker
formula a ferromagnetic graphene junction with a temperature gradient across
the system, is studied. We calculate the thermally induced charge and spin
current as well as the thermoelectric voltage (Seebeck effect) in the linear
and nonlinear regimes. Our calculation revealed that due to the electron-hole
symmetry, the charge Seebeck coefficient is, for an undoped magnetic graphene,
an odd function of chemical potential while the spin Seebeck coefficient is an
even function regardless of the temperature gradient and junction length. We
have also found with an accurate tuning external parameter, namely the exchange
filed and gate voltage, the temperature gradient across the junction drives a
pure spin current without accompanying the charge current. Another important
characteristic of thermoelectric transport, thermally induced current in the
nonlinear regime, is examined. It would be our main finding that with
increasing thermal gradient applied to the junction the spin and charge
thermovoltages decrease and even become zero for non-zero temperature bias.
