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Spin Seebeck Effect

Yu Group Meeting. Spin Seebeck Effect. Lv Chao ( 吕超 ) 2018.02.05. Contents. 1. 2. 3. Background and introduction. Some potential applications. Research progress. Background and introduction. 1. Thermoelectric generator.

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Spin Seebeck Effect

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  1. Yu Group Meeting Spin Seebeck Effect Lv Chao (吕超) 2018.02.05

  2. Contents 1 2 3 Background and introduction Some potential applications Research progress

  3. Background and introduction 1 Thermoelectric generator • Thermoelectric Effect Temperature measurement Thermal cyclers Electricity Heat

  4. Background and introduction 1 • Seebeck Effect

  5. Background and introduction 1 • The Seebeck effect refers to the production of a longitudinal electromotive force induced by the temperature gradient. • The Peltier effect refers to the evolution of the longitudinal heat current Q, which is induced by the electric current J across an isothermal junction of two terminals.

  6. Background and introduction 1 • ZT is the primary parameter of the thermoelectric potential of a material. • For a material to be a good thermoelectric material, it must have a large ZT, which means in order to achieve a large ZT, one must increase the Seebeck coefficient and electrical conductivity and decrease the thermal conductivity. Seebeck coefficient Electrical conductivity Temperature Thermal conductivity

  7. Background and introduction 1 Thermoelectrics in the global landscape of energy conversion Timeline of the maximum ZT values for several representative families of TE materials Jian He, et al. Science (2017)

  8. Background and introduction 1 • Spintronics Spin, a new degree of freedom.

  9. Background and introduction 1 Chen Xiao-Bin, et al. Acta Phys. Sin. (2015) Goennenwein, et al. Nature Nanotech. (2012)

  10. Research progress 2 • Spin Hall effect (SHE) and inverse spin Hall effect (ISHE) Spin Hall coefficient Spin current Spin polarized vector B. F. Miao, et al. PRL (2013)

  11. Research progress 2 • Spin Seebeck Effect in FM metal In 2008, Saitoh et al firstly demonstrated that when a ferromagnetic film is placed under the influence of a temperature gradient, a spin current is injected from the ferromagnetic film into the attached nonmagnetic metals with the signal observed over a macroscopic scale of several millimeters. K. Uchida, E. Saitoh, et al. Nature (2008 )

  12. Research progress 2 The spin counterpart of such a thermocouple is the spin current/accumulation that is induced by a temperature difference applied across a ferromagnet, interpreting the two spin channels as the two conductors. K. Uchida, E. Saitoh, et al. Nature (2008 )

  13. Research progress 2 • Magnon- droven SSE i) The inverse spin Hall effect, which converts the spin current into an electrical voltage; ii) Thermally activated spin pumping at the FN interface driven by the phonon-magnon temperature difference; iii) The phonon-magnon temperature difference profile induced by the temperature bias applied over a ferromagnetic film. This effect by spin pumping at the contact that is proportional to the spin-mixing conductance of the interface, the inverse of a temperature-dependent magnetic coherence volume, and the difference between the magnon temperature in the ferromagnet and the electron temperature in the normal metal. Jiang Xiao, et al. PRB (2010)

  14. Research progress 2 • SSE in the insulator K. Uchida, Saitoh, et al. Nature Mater. (2010)

  15. Research progress 2 K. Uchida, Saitoh, et al. Nature Mater. (2010)

  16. Research progress 2 • SSE in the FM half-metal Heusler compound Co2MnSi K. Takanashi, et al. PRB. (2011)

  17. Research progress 2 • SSE in the FM semiconductor K. Takanashi, et al. PRB. (2011)

  18. Research progress 2 • Position dependence As phonons can pass through even an insulating substrate, the distribution function of magnons in the Ni81Fe19 wire is modulated by the non-equilibrium phonons through the magnon-phonon interaction. K. Uchida, Satioh et al. Nature Mater. (2011)

  19. Research progress 2 • Longitudinal SSE Niizeki T, et al. AIP Adv. (2015)

  20. Some potential applications 3 • Thermoelectric generation Niizeki T, et al. AIP Adv. (2015)

  21. Some potential applications 3 • Spin thermoelectric coating Niizeki T, et al. AIP Adv. (2015)

  22. Some potential applications 3 What’s more about spintronics?

  23. Thank you!

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