It is demonstrated both analytically and numerically that the properties of spin wave modes excited by a current-driven nanocontact of length $L$ in a quasi-one-dimensional magnetic waveguide magnetized by a perpendicular bias magnetic field $H_e$ are qualitatively different from the properties of spin waves excited by a similar nanocontact in a two-dimensional unrestricted magnetic film (“free layer”). In particular, there is an optimum nanocontact length $L_{\mathrm{opt}}$ corresponding to the minimum critical current of the spin wave excitation. This optimum length is determined by the magnitude of $H_e$, the exchange length, and the Gilbert dissipation constant of the waveguide material. Also, for $L<L_{\mathrm{opt}}$ the wavelength λ (and the wave number $k$) of the excited spin wave can be controlled by the variation of $H_e$ (λ decreases with the increase of $H_e$), while for $L>L_{\mathrm{opt}}$ the wave number $k$ is fully determined by the contact length $L$ ($k\sim 1/L$), similar to the case of an unrestricted two-dimensional free layer.

• Received 20 May 2013

DOI:https://doi.org/10.1103/PhysRevB.88.014417