Papers by Author: Victor Vega

Abstract: Highly ordered arrays of Fe antidot films were fabricated by thermal vapor deposition technique using nanoporous alumina templates. The film thickness varies from 20 up to 100 nm, and the antidots array has about 50 nm in diameter and 105 nm of periodic interspacing. Scanning electron microscopy and atomic force microscopy measurements confirmed that the Fe antidots film retains the well-ordered hexagonal structure of the nanoporous alumina template. Meanwhile, the micromagnetic structure was studied by magnetic force microscopy and SQUID measurements. A stripe magnetic domain pattern featuring a large out-of-plane magnetization component is found in the films. Noteworthily, the magnetic domains are not pinned by the nanopores but, on the contrary, several antidots are included in each magnetic domain. According to the magnetic measurements, the easy magnetization axis of the Fe antidot array remains in the film plane, while the hard one lies perpendicular to the plane, which can be explained on the basis of the different contributions of the nanoholes to the total magnetic anisotropy of the antidots film.

Abstract: Glass-coated Cu-Mn-Ga microwires were fabricated by Taylor-Ulitovsky technique. By means of energy dispersive spectroscopy microanalysis, an average alloy composition of Cu56Ga28Mn16 was determined. The temperature dependence of magnetization measured at a low magnetic field showed the coexistence of two ferromagnetic phases. The Curie temperature of one phase is 125 K and above room temperature for the other one. X-ray diffraction at room temperature and at 100 K reflects the presence of the same three crystalline phases corresponding to the cubic B2 Cu-Mn-Ga structure as a main phase and the minor phases of fcc Cu rich solid solution with Mn and Ga and the monoclinic CuO.