Abstract
In the search for new physical properties of S/F structures, we have found that the superconductor critical current can be controlled by the domain state of the neighboring ferromagnet. The superconductor is a thin wire of thickness ds ≈2ξS. Nb/Co and Nb/Py (Permalloy Ni80Fe20) bilayer structures were grown with a significant magnetic anisotropy. Critical current measurements of Nb/Co structures with ferromagnet thickness dF > 30 nm show sudden drops in two very defined steps when the measurements are made along the hard axes direction (i.e. current track parallel to hard anisotropy axes direction). These drops disappear when they are made along the easy axis direction or when the ferromagnet thickness is below 30 nm. The drops are accompanied by vortex flux flow. In addition magnetorestistance measurements close to TC show a sharp increase near saturation fields of the ferromagnet. Similar results are reproduced in Nb/Py bilayer structure with the ferromagnet thickness dF ~ 50 nm along the easy anisotropy axes. These results are explained as being due to spontaneous vortex formation and flow induced by Bloch domain walls of the ferromagnet underneath. We argue these Bloch domain walls produce a 2D vortex-antivortex lattice structure.
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Z. Radović, M. Ledvij, L. Dobrosavljević-Grujić, A.I. Buzdin, J.R. Clem, Phys. Rev. B 44, 759 (1991)
V.V. Ryazanov, V.A. Oboznov, A.Y. Rusanov, A.V. Veretennikov, A.A. Golubov, J. Aarts, Phys. Rev. Lett. 86, 2427 (2001)
J.S. Jiang, D. Davidović, D.H. Reich, C.L. Chien, Phys. Rev. Lett. 74, 314 (1995)
R.J. Kinsey, G. Burnell, M.G. Blamire, IEEE Trans. Appl. Supercond. 11, 904 (2001)
M. Houset, A.I. Buzdin, Phys. Rev. B 74, 214507 (2006)
A. Rusanov, M. Hesselberth, S. Habraken, J. Aarts, Physica C 404, 322 (2004)
A.Y. Rusanov, M. Hesselberth, J. Aarts, A.I. Buzdin, Phys. Rev. Lett. 93, 57002 (2004)
V.V. Ryazanov, V.A. Oboznov, A.S. Prokof’ev, S.V. Dubonos, JETP Lett. 77, 39 (2003)
I.S. Burmistrov, N.M. Chtchelkatchev, Phys. Rev. B 72, 144520 (2005)
R. Steiner, P. Ziemann, Phys. Rev. B 74, 94504 (2006)
C. Bell, S. Tursucu, J. Aarts, Phys. Rev. B 74, 214520 (2006)
In most of our meassurements well bellow TC we did not observed flux flow at the dip region but an abrupt reduction of the critical current value. However as shown in Figure [SEE TEXT] close to TC the pinning barrier is easily overcomed by thermalactivation
M. Löhndorf, A. Wadas, H.A.M. van den Berg, R. Wiesendanger, Appl. Phys. Lett. 68, 25 (1996)
S. Methfessel, S. Middelhoek, H. Thomas, IBM Journal 4, 96 (1959)
A. Stankiewiczyz, S.J. Robinsonz, G.A. Gehringzx, V.V. Tarasenkoy, J. Phys: Condens. Matter 9, 1019 (1997)
A.Y. Rusanov, T.E. Golikova, S.V. Egorov. JETP Lett. 87, 175 (2008)
E.J. Patiño, Study of The Influence of Domain Walls in The Superconductor/Ferromagnet Proximity Effect, Ph.D. thesis (non-published), CambridgeUniversity, 2005
M. Lange, M.J. Van Bael, Y. Bruynseraede, V.V. Moshchalkov, Phys. Rev. Lett. 90, 197006 (2003)
Z. Yang, M. Lange, A. Volodin, R. Szymczak, V.V. Moshchalkov, Nature Mat. 3, 793 (2004)
H. Hilgenkamp, Ariando, H.-J.H. Smilde, D.H.A. Blank, G. Rijnders, H. Rogalla, J.R. Kirtley, C.C. Tsuei, Nature 422, 50 (2003)
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Patiño, E., Bell, C. & Blamire, M. Sudden critical current drops induced in S/F structures. Eur. Phys. J. B 68, 73–77 (2009). https://doi.org/10.1140/epjb/e2009-00074-x
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DOI: https://doi.org/10.1140/epjb/e2009-00074-x