2008/10/09 by Andre Thiaville, André Thiaville, Yoshinobu Nakatani
Materials Science · Physics and Astronomy · #Chemical and Physical Properties of Materials #Magnetic properties of thin films #Quantum and electron transport phenomena #cond-mat.other
paper · pdf · doi:10.1063/1.3006005
to be published in Journal of Applied Physics
arxiv created 2008/10/09 · openalex publication_date 2008/11/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
Upon passing an ac electrical current along magnetic micro- or nanostrips, the measurement of a dc voltage that depends sensitively on current frequency and applied field has been recently reported by Yamaguchi et al. [Appl. Phys. Lett. 90, 182507 (2007); e-print arXiv:0710.2172; Phys. Rev. B 78, 104401 (2008)]. It was attributed to the excitation of spin waves by the spin transfer torque, leading to a time-varying anisotropic magnetoresistance, and by mixing of ac current and resistance to a dc. voltage. We have performed a quantitative analysis by micromagnetics including the spin transfer torque terms considered usually of this situation. The signals found from the spin transfer torque effect are several orders of magnitude below the experimental values, even if a static inhomogeneity of magnetization (the so-called ripple) is taken into account. On the other hand, the presence of a small nonzero average Oersted field is shown to be consistent with the full set of experimental results, both qualitatively and quantitatively. We examine, quantitatively, several sources for this average field and point to the contacts of the sample as a likely origin.