Anisotropic superconductivity and vortex dynamics in magnetially coupled F/S and F/S/F hybrids.

Conference · Sat Jan 01 00:00:00 EST 2011 · J. Superconduct. Novel Magn.

DOI:https://doi.org/10.1007/s10948-010-0880-z· OSTI ID:1014815

Karapetrov, G; Belkin, A; Iavarone, M; Fedor, J; Novosad, V; Milosevic, M V; Peeters, F M ^[1]

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1. Materials Science Division

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{sub 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.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC02-06CH11357
• OSTI ID: 1014815
• Report Number(s): ANL/MSD/CP-67444; TRN: US201111%%356
• Journal Information: J. Superconduct. Novel Magn., Vol. 24, Issue 5 ; Jan. 2011; Conference: International Conference on Superconductivity and Magnetism 2010 (ICSM 2010); Apr. 25, 2010 - Apr. 30, 2010; Antalya, Turkey
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANISOTROPY
CHAINS
COHERENCE LENGTH
CRITICAL TEMPERATURE
DOMAIN STRUCTURE
FOCUSING
INDUCTION
MAGNETIC FLUX
MAGNETISM
MAGNETIZATION
MODULATION
NUCLEATION
ORDER PARAMETERS
PHASE DIAGRAMS
SCANNING TUNNELING MICROSCOPY
SUPERCONDUCTIVITY
SUPERCONDUCTORS
VORTICES