Antiferromagnetic Spin Seebeck Effect

We report on the observation of the spin Seebeck effect in antiferromagnetic ${\mathrm{MnF}}_{2}$. A device scale on-chip heater is deposited on a bilayer of ${\mathrm{MnF}}_{2}$ (110) $(30\text{ }\text{ }\mathrm{nm})/\mathrm{Pt}$ (4 nm) grown by molecular beam epitaxy on a ${\mathrm{MgF}}_{2}$ (110) substrate. Using Pt as a spin detector layer, it is possible to measure the thermally generated spin current from ${\mathrm{MnF}}_{2}$ through the inverse spin Hall effect. The low temperature (2--80 K) and high magnetic field (up to 140 kOe) regime is explored. A clear spin-flop transition corresponding to the sudden rotation of antiferromagnetic spins out of the easy axis is observed in the spin Seebeck signal when large magnetic fields ($>9\text{ }\text{ }\mathrm{T}$) are applied parallel to the easy axis of the ${\mathrm{MnF}}_{2}$ thin film. When the magnetic field is applied perpendicular to the easy axis, the spin-flop transition is absent, as expected.