Magnetic and Transport Properties of Micron Size Magnetic Participate Arrays Fabricated on a 2D Superconducting Nb Films and Sub-Micron Magnetic Wires

Abstract

ABSTRACTMicron size particulate arrays of amorphous R-Co (R = Sm and Gd) alloys with a thickness of 200 nm were fabricated on top of a 20 nm thick Nb film by means of e-beam lithography and sputter deposition. The arrays consist of 2 × 2 μm2 square particles with a spatial periodicity of 4 μm along an edge of the square. Interesting oscillations due to the fluxoid quantization were observed both in the transition lines and the magnetization curves of the underlying Nb film. The superconducting state of the Nb film was found to be modulated by stray fields of the square magnetic particles.Sub-micron size ferromagnetic Fe wires were also prepared in order to investigate the magnetoresistance effect associated with pinning and depinning processes of a magnetic domain wall confined in the wire. Low temperature transport, Lorentz microscopy and electron holography measurements demonstrated a clear change in resistivity associated with the depinning of a pinned single domain wall.