1,955 research outputs found
Direct and inverse measurement of thin films magnetostriction
Two techniques of measurements of thin film magnetostriction are compared:
direct, when changes of the substrate curvature caused by the film
magnetization are controlled, and inverse ("indirect"), when the modification
of the magnetic anisotropy induced by the substrate deformation (usually
bending) is measured. We demonstrate how both the elastic strength of the
substrate and the effective magneto-mechanical coupling between the substrate
deformation and magnetic anisotropy of the film depend on different conditions
of bending. Equations to be used for magnetostriction value determination in
typical cases are given and critical parameters for the corresponding
approximations are identified.Comment: 13 pages, 10 figures, 1 table, submitted to JMM
Thickness dependent magnetic anisotropy of ultrathin LCMO epitaxial thin films
The magnetic properties of La0.7Ca0.3MnO3 (LCMO) manganite thin films were
studied with magnetometry and ferromagnetic resonance as a function of film
thickness. They maintain the colossal magnetoresistance behavior with a
pronounced metal-insulator transition around 150-200 K, except for the very
thinnest films studied (3 nm). Nevertheless, LCMO films as thin as 3 nm remain
ferromagnetic, without a decrease in saturation magnetization, indicating an
absence of dead-layers, although below approx. 6 nm the films remain insulating
at low temperature. Magnetization hysteresis loops reveal that the magnetic
easy axes lie in the plane of the film for thicknesses in the range of 4-15 nm.
Ferromagnetic resonance studies confirm that the easy axes are in-plane, and
find a biaxial symmetry in-plane with two, perpendicular easy axes. The
directions of the easy axes with respect to the crystallographic directions of
the cubic SrTiO3 substrate differ by 45 degrees in 4 nm and 15 nm thick LCMO
films.Comment: Presented at Intermag conference (Madrid, 2008). Accepted for
publication in IEEE Transactions on Magnetic
Investigation of single crystal ferrite thin films
Materials suitable for use in magnetic bubble domain memories were developed for aerospace applications. Practical techniques for the preparation of such materials in forms required for fabrication of computer memory devices were considered. The materials studied were epitaxial films of various compositions of the gallium-substituted yttrium gadolinium iron garnet system. The major emphasis was to determine their bubble properties and the conditions necessary for growing uncracked, high quality films
Magnetism in reduced dimensions
We propose a short overview of a few selected issues of magnetism in reduced
dimensions, which are the most relevant to set the background for more
specialized contributions to the present Special Issue. Magnetic anisotropy in
reduced dimensions is discussed, on a theoretical basis, then with experimental
reports and views from surface to single-atom anisotropy. Then conventional
magnetization states are reviewed, including macrospins, single domains,
multidomains, and domain walls in stripes. Dipolar coupling is examined for
lateral interactions in arrays, and for interlayer interactions in films and
dots. Finally thermally-assisted magnetization reversal and superparamagnetism
are presented. For each topic we sought a balance between well established
knowledge and recent developments.Comment: 13 pages. Part of a Special Issue of the C. R. Physique devoted to
spinelectronics (2005
Growth-Induced In-Plane Uniaxial Anisotropy in VO/Ni Films
We report on a strain-induced and temperature dependent uniaxial anisotropy
in VO/Ni hybrid thin films, manifested through the interfacial
strain and sample microstructure, and its consequences on the angular dependent
magnetization reversal. X-ray diffraction and reciprocal space maps identify
the in-plane crystalline axes of the VO; atomic force and scanning
electron microscopy reveal oriented rips in the film microstructure.
Quasi-static magnetometry and dynamic ferromagnetic resonance measurements
identify a uniaxial magnetic easy axis along the rips. Comparison with films
grown on sapphire without rips shows a combined contribution from strain and
microstructure in the VO/Ni films. Magnetization reversal
characteristics captured by angular-dependent first order reversal curve
measurements indicate a strong domain wall pinning along the direction
orthogonal to the rips, inducing an angular-dependent change in the reversal
mechanism. The resultant anisotropy is tunable with temperature and is most
pronounced at room temperature, which is beneficial for potential device
applications
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