title: Observation of spin Seebeck contribution to the transverse thermopower in Ni-Pt and MnBi-Au bulk nanocomposites.
abstract: Transverse thermoelectric devices produce electric fields perpendicular to an incident heat flux. Classically, this process is driven by the Nernst effect in bulk solids, wherein a magnetic field generates a Lorentz force on thermally excited electrons. The spin Seebeck effect also produces magnetization-dependent transverse electric fields. It is traditionally observed in thin metallic films deposited on electrically insulating ferromagnets, but the films' high resistance limits thermoelectric conversion efficiency. Combining Nernst and spin Seebeck effect in bulk materials would enable devices with simultaneously large transverse thermopower and low electrical resistance. Here we demonstrate experimentally that this is possible in composites of conducting ferromagnets (Ni or MnBi) containing metallic nanoparticles with strong spin-orbit interactions (Pt or Au). These materials display positive shifts in transverse thermopower attributable to inverse spin Hall electric fields in the nanoparticles. This more than doubles the power output of the Ni-Pt materials, establishing proof of principle that the spin Seebeck effect persists in bulk nanocomposites.
authors.affiliation: Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Boona
authors.affiliation: Department of Inorganic and Physical Chemistry, Ghent University, Gent B-9000, Belgium.
authors.forename: Koen
authors.initials: K
authors.lastname: Vandaele
authors.affiliation: Center for Electron Microscopy and Analysis, The Ohio State University, Columbus, Ohio 43212, USA.|Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: Isabel N
authors.initials: IN
authors.lastname: Boona
authors.affiliation: Center for Electron Microscopy and Analysis, The Ohio State University, Columbus, Ohio 43212, USA.|Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: David W
authors.initials: DW
authors.lastname: McComb
authors.affiliation: Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, Ohio 43210, USA.|Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210, USA.|Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Heremans