Spin Seebeck voltage enhancement by Mn system metals insertion at the interface between YIG and nonmagnetic layer

The spin Seebeck voltage was successfully increased by IrMn or Mn insertion into the interface Y₃Fe₅O₁₂ and nonmagnetic Pt and TaW with positive and negative spin Hall angle, respectively. The magnitude of the spin Seebeck coefficient |S| of the samples with IrMn and Mn were higher than that with Ru insertion, which indicates that the existence of the magnetic moment is important for the spin Seebeck coefficient. Furthermore, |S| of the samples with IrMn and Mn were higher than oxide antiferromagnetic NiO, which suggests the metallic layer insertion is effective for enlarging |S| owing to the relatively long spin diffusion length. Since the inserted IrMn and NiO take the paramagnetic states as well as Mn, it is supposed that the spin fluctuation in the paramagnetic insertion layers play an important role in enhancing the spin current.