Berlin 2008 – scientific programme

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MA: Fachverband Magnetismus

MA 32: Postersession II: Spinstruct./Phase Trans. (1-10); Spinelectronics (11-15); Thin Films (16 - 36); Particles/Clusters (37-45); Multiferroics (46-54); Spindynamics/Spin Torque (55 - 76); Post Deadlines (77-79)

MA 32.39: Poster

Friday, February 29, 2008, 11:15–14:00, Poster E

Surface anisotropy and vortex states in ferromagnetic nanowires and nanotubes — •Andrei A. Leonov^1,2, Ulrich K. Rößler¹, and Alexei N. Bogdanov^1,2 — ¹IFW Dresden — ²Donetsk Institute for Physics and Technology

In ferromagnetic nanowires and nanotubes magnetic couplings induced by lateral surfaces can overcome the stray-field forces and stabilize inhomogeneous states where the magnetization vector rotates along or perpendicular to radial directions as Néel or Bloch vortex, respectively [1]. Depending on the surface anisotropy constants vortices are formed by a continuous rotation of the magnetization vector away from the homogeneous state with collinear longitudinal magnetization. Depending on the material and geometrical parameters different types of Néel and Bloch vortices can exist in nanowires and nanotubes. The phase diagram of the solutions includes stability regions of different vortex states and homogeneous phases with longitudinal or transverse magnetization separated by first- or second-order transition lines. Signatures of vortex states are discussed in relation to experimental observations on magnetization processes in magnetic nanowires. In particular, vortex states may be responsible for certain features of the magnetoresistance in nanowires. For nanotubes solutions for twisted states exist similar to the inhomogeneous phases in ferromagnetic nanolayers [2].

[1] U.K. Rößler, A. N. Bogdanov, K.-H. Müller, IEEE Trans. Magn. 38 (2002) 2586; [2] A. N. Bogdanov, U.K. Rößler, K.-H. Müller, J. Magn. Magn. Mat. 238 (2002) 155.