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Anisotropic Superconductivity and Vortex Dynamics in Magnetically Coupled F/S and F/S/F Hybrids
Journal article   Peer reviewed

Anisotropic Superconductivity and Vortex Dynamics in Magnetically Coupled F/S and F/S/F Hybrids

G. Karapetrov, A. Belkin, M. Iavarone, J. Fedor, V. Novosad, M. V. Milosevic and F. M. Peeters
Journal of superconductivity and novel magnetism, v 24(1-2), pp 905-910
01 Jan 2011

Abstract

Physical Sciences Physics Physics, Applied Physics, Condensed Matter Science & Technology
Magnetically coupled superconductor-ferromagnet hybrids offer advanced routes for nanoscale control of superconductivity. Magnetotransport characteristics and scanning tunneling microscopy images of vortex structures in superconductor-ferromagnet hybrids reveal rich superconducting phase diagrams. Focusing on a particular combination of a ferromagnet with a well-ordered periodic magnetic domain structure with alternating out-of-plane component of magnetization, and a small coherence length superconductor, we find directed nucleation of superconductivity above the domain wall boundaries. We show that near the superconductor-normal state phase boundary the superconductivity is localized in narrow mesoscopic channels. In order to explore the Abrikosov flux line ordering in F/S hybrids, we use a combination of scanning tunneling microscopy and Ginzburg-Landau simulations. The magnetic stripe domain structure induces periodic local magnetic induction in the superconductor, creating a series of pinning-anti-pinning channels for externally added magnetic flux quanta. Such laterally confined Abrikosov vortices form quasi-1D arrays (chains). The transitions between multichain states occur through propagation of kinks at the intermediate fields. At high fields we show that the system becomes nonlinear due to a change in both the number of vortices and the confining potential. In F/S/F hybrids we demonstrate the evolution of the anisotropic conductivity in the superconductor that is magnetically coupled with two adjacent ferromagnetic layers. Stripe magnetic domain structures in both F-layers are aligned under each other, resulting in a directional superconducting order parameter in the superconducting layer. The conductance anisotropy strongly depends on the period of the magnetic domains and the strength of the local magnetization. The anisotropic conductivity of up to three orders of magnitude can be achieved with a spatial critical temperature modulation of 5% of T (c). Induced anisotropic properties in the F/S and F/S/F hybrids have a potential for future application in switching and nonvolatile memory elements operating at low temperatures.

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Domestic collaboration
International collaboration
Web of Science research areas
Physics, Applied
Physics, Condensed Matter
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