2002/09/23 by Edward McCann, Vladimir I. Fal’ko, Vladimir I. Fal'ko · 3 citations
Physics and Astronomy · #Condensed matter physics #Electrical resistivity and conductivity #Electron #Ferromagnetism #Magnetic field #Magnetic properties of thin films #Magnetization #Magnon #Mesoscopic physics #Physics #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #Quantum mechanics #Quantum tunnelling #Seebeck coefficient #Tunnel junction #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevb.66.134424
published as Phys. Rev. B 66, 134424 (2002) · 9 pages, 4 eps figures
arxiv created 2002/09/23 · openalex publication_date 2002/10/30 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present a theoretical description of the thermopower due to magnon-assisted tunneling in a mesoscopic tunnel junction between two ferromagnetic metals. The thermopower is generated in the course of thermal equilibration between two baths of magnons, mediated by electrons. For a junction between two ferromagnets with antiparallel polarizations, the ability of magnon-assisted tunneling to create thermopower SAP depends on the difference between the size \ensuremathΠ_\ensuremath\uparrow,\ensuremath\downarrow of the majority- and minority-band Fermi surfaces and it is proportional to a temperature-dependent factor (kBT/\ensuremathωD)3/2 where \ensuremathωD is the magnon Debye energy. The latter factor reflects the fractional change in the net magnetization of the reservoirs due to thermal magnons at temperature T (Bloch's T3/2 law). In contrast, the contribution of magnon-assisted tunneling to the thermopower SP of a junction with parallel polarizations is negligible. As the relative polarizations of ferromagnetic layers can be manipulated by an external magnetic field, a large difference \ensuremathΔS=SAP\ensuremath-SP\ensuremath≈SAP\ensuremath∼\ensuremath-(kB/e)f(\ensuremathΠ_\ensuremath\uparrow,\ensuremathΠ_\ensuremath\downarrow)(kBT/\ensuremathωD)3/2 results in a magnetothermopower effect. This magnetothermopower effect becomes giant in the extreme case of a junction between two half-metallic ferromagnets, \ensuremathΔS\ensuremath∼\ensuremath-kB/e.