RT Journal Article T1 Magnetic instabilities along the superconducting phase boundary of Nb/Ni multilayers A1 Joshi, Amish G A1 Kryukov, Sergiy A. A1 De Long, Lance E. A1 González Herrera, Elvira María A1 Navarro Palma, Elena A1 Villegas, Javier E. A1 Vicent López, José Luis AB We report vibrating reed and superconducting quantum interference device magnetometer data that exhibit prominent dips or oscillations of the superconducting (SC) onset temperature, Delta T(C)(H)approximate to 0.01-0.7 K, for a [Nb(23 nm)/Ni(5 nm)](5) multilayer (ML) in dc magnetic fields applied nearly parallel to the ML plane. The vibrating reed data exhibit reproducible structures below T(C) that may reflect multiple SC transitions, but they are sensitive to ac field amplitude and dc field orientation. This striking behavior poses challenges for theoretical and experimental investigations of interfaces between SC and ferromagnetic layers that involve magnetic pair breaking effects, "pi phase shifts" of the SC order parameter, and exotic ("LOFF") pairing states. Alternatively, the anomalies may mark dynamical instabilities within a confined, strongly anisotropic Abrikosov vortex lattice. PB American Institute of Physics SN 0021-8979 YR 2007 FD 2007-05-01 LK https://hdl.handle.net/20.500.14352/52121 UL https://hdl.handle.net/20.500.14352/52121 LA eng NO © 2007 American Institute of Physics.Research at University of Kentucky supported by U.S. Department of Energy and Kentucky Science and Engineering Foundation. Research at Universidad Complutense supported by Spanish Ministerio de Educacion y Ciencia, Comunidad de Madrid y Santander-UCM. One of the authors (A.G.J.) was supported by an Indian Department of Science and Technology BOYSCAST Fellowship No. SR/BY/P-01/ 04. NO Spanish Ministerio de Educacion y Ciencia NO Comunidad de Madrid NO Santander-UCM DS Docta Complutense RD 7 abr 2025