Thermally driven spin injection from a ferromagnet into a non-magnetic metal Slachter, A.; Bakker, F. L.; Adam, J-P.; van Wees, B. J.Published in: Nature Physics DOI: 10.1038/NPHYS1767IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite from it. Please check the document version below. Document VersionPublisher's PDF, also known as Version of record Publication date: 2010Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Slachter, A., Bakker, F. L., Adam, J-P., & van Wees, B. J. (2010). Thermally driven spin injection from a ferromagnet into a non-magnetic metal. Nature Physics, 6(11), 879-882. https://doi.org/10.1038/NPHYS1767 Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. van WeesCreation, manipulation and detection of spin-polarized carriers are the key elements of spin-based electronics 1,2 . Most practical devices 3-5 use a perpendicular geometry in which the spin currents are accompanied by charge currents. In recent years, new sources of pure spin currents (that is, transport of spin angular momentum without charge currents) have been demonstrated 6-9 and applied 10-12 . Here we demonstrate a conceptually new source of pure spin current driven by the flow of heat across the interface between a ferromagnet and a non-magnetic metal. This spin current is generated because, in a ferromagnet, the Seebeck effect-which describes the generation of a voltage as a result of a temperature gradient-is spin dependent 13,14 . We studied this new source of spin currents experimentally in a non-local lateral geometry and developed a three-dimensional model that describes the heat, charge and spin transport in this geometry, enabling us to quantify this process 15 . We obtain a spin-dependent Seebeck coefficient for Permalloy of −3.8 µV K −1 , suggesting that thermally driven spin injection is a feasible alternative for electrical spin injection in, for example, spin-transfer-torque experiments 16 .The interplay of spin-dependent conductivity and thermoelectricity has been known since half a century ago, when it was used to describe the conventional Seebeck effect of ferromagnetic metals 17 . The discovery of the giant magnetoresistance effect 3 sparked the interest of the community in spin-dependent conductivity and new spin electronics that still exists today 4,5,8,18 . Owing to experimental difficulties in controlling heat flows it was only very recently that thermoelectric spintronics was investigated 19,20 , leading to the new field of spin caloritronics 13 . A relevant example is given in ref. 9, which interpret...

We present an analytical calculation of the velocity of a single 180 • domain wall in a magnetic structure with reduced thickness and/or lateral dimension under the combined action of an external applied magnetic field and an electrical current. As for the case of field-induced domain wall propagation in thick films, two motion regimes with different mobilities are obtained, below and far above the so-called Walker field. Additionally, for the case of current induced motion, a Walker-like current density threshold can be defined. When the dimensions of the system become comparable to the domain wall width, the threshold field and current density, stating the wall's internal structure stability, are reduced by the same geometrical demagnetising factor which accounts for the confinement. This points out the fact that the velocity dependence over an extended field/current range and the knowledge of the Walker breakdown are mandatory to draw conclusions about the phenomenological Gilbert damping parameter tuning the magnetisation dynamics.