Antiferromagnetic Spin Seebeck Effect

We report on the observation of the spin Seebeck effect in antiferromagnetic MnF₂. A device scale on-chip heater is deposited on a bilayer of MnF₂ (110) (30 nm)/Pt (4 nm) grown by molecular beam epitaxy on a MgF₂ (110) substrate. Using Pt as a spin detector layer, it is possible to measure the thermally generated spin current from MnF₂ 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 T) are applied parallel to the easy axis of the MnF₂ thin film. When the magnetic field is applied perpendicular to the easy axis, the spin-flop transition is absent, as expected.