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تسجيل مستخدم جديدProximity-induced density-of-states oscillations in a superconductor/strong-ferromagnet system
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We have measured the evolution of the tunneling density of states (DOS) in superconductor/ferromagnet (S/F) bilayers with increasing F-layer thickness, where F in our experiment is the strong ferromagnet Ni. As a function of increasing Ni thickness, we detect multiple oscillations in the DOS at the Fermi energy from differential conductance measurements. The features in the DOS associated with the proximity effect change from normal to inverted twice as the Ni thickness increases from 1 to 5 nm.
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We have studied the proximity-induced superconducting triplet pairing in CoO$_x$/Py1/Cu/Py2/Cu/Pb spin-valve structure (where Py = Ni$_{0.81}$Fe$_{0.19}$). By optimizing the parameters of this structure we found a triplet channel assisted full switch
ing between the normal and superconducting states. To observe an isolated triplet spin-valve effect we exploited the oscillatory feature of the magnitude of the ordinary spin-valve effect $Delta T_c$ in the dependence of the Py2-layer thickness $d_{Py2}$. We determined the value of $d_{Py2}$ at which $Delta T_c$ caused by the ordinary spin-valve effect (the difference in the superconducting transition temperature $T_c$ between the antiparallel and parallel mutual orientation of magnetizations of the Py1 and Py2 layers) is suppressed. For such a sample a pure triplet spin-valve effect which causes the minimum in $T_c$ at the orthogonal configuration of magnetizations has been observed.
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tory behavior of the superconducting pair wave function in the F-layer. Then, we concentrate on recent theoretical predictions for S/F layer systems. These are a) generation of odd triplet superconductivity in the F-layer and b) ferromagnetism induced in the S-layer below the superconducting transition temperature $T_{c}$ (inverse proximity effect). The second part of the review is devoted to discussion of experiments relevant to the theoretical predictions of the first part. In particular, we present results of measurements of the critical temperature $T_{c}$ as a function of the thickness of F-layers and we review experiments indicating existence of odd triplet superconductivity, cryptoferromagnetism and inverse proximity effect.
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