0000000000315810
AUTHOR
Ulrich Gradmann
Magnetic surface anisotropies in NiFe-alloy films: separation of intrinsic Néel-type from strain relaxation contributions
Abstract Magnetic surface anisotropies (MSA) in NiFe/Cu(1 1 1) films were investigated experimentally, for varying compositions of the NiFe alloy. By restricting the measurements to the pseudomorphic range, the pure intrinsic Neel-type anisotropy could be isolated without strain relaxation contributions. The intrinsic MSA of the xNi(1−x)Fe/Cu(1 1 1) interface varies linearly with composition x between easy plane for pure Ni to perpendicular for x=60 and 48%. It vanishes near the permalloy composition x=80%.
Problems of electron detection in Depth-Selective Conversion Electron Mössbauer Spectroscopy
Applications of Depth-Selective Conversion Electron Mossbauer Spectroscopy (DCEMS) are limited by the long measuring times needed for collecting sufficient data statistics. To shorten the recording time, the background should be reduced and the detection efficiency for conversion electrons should be improved. For57Co/57Fe DCEMS, systematic studies were performed to investigate the origin, shape, and structure of the background components in DCEMS data distributions for various samples using channeltrons and low-noise scintillation counters as electron detectors.
Reorientation of magnetization states in Fe-nanostripe arrays on stepped W(110) caused by adsorption of CO, H2 and O2
Abstract Fe-Nanostripe arrays of alternating double layer (DL) and monolayer (ML) stripes were grown on stepped W(1 1 0) surfaces by MBE. Magnetic properties were measured in situ in UHV using the polar and longitudinal magneto-optical Kerr effect (MOKE) during exposure to CO, H2 and O2. The longitudinal Kerr signal increases and the polar signal decreases with increasing exposure of all three gases. A sudden onset of perpendicular remanence was observed at exposures characteristic for each particular gas.
Morphology and magnetism of Fe on vicinal W(110) surfaces with different step orientation
Abstract Nanostructures of monolayer height of single-crystalline Fe(1 1 0) films were grown on stepped W(1 1 0) surfaces. The growth mode strongly depends on the step orientation of the substrate. Continuous stripes are formed at steps along the [1 0 0] direction whereas triangular shaped islands grow on substrates with [1 −1 0]-oriented step edges. No ferromagnetic order was found in submonolayer films grown on [1 −1 0]-steps. The nanostripe array on [1 0 0] steps shows a ferromagnetic phase-transition with a critical behavior different from the Ising-like phase transition observed for submonolayer films grown on smooth W(1 1 0). The magnetic easy axis in the samples is oriented parallel …
Dipolar superferromagnetism in monolayer nanostripes of Fe(110) on vicinal W(110) surfaces
By epitaxial growth of Fe on a vicinal W~110! substrate, densely spaced and continuous monolayer stripes of Fe~110! were prepared, directed along @001#. They exhibit a sharp phase transition to ferromagnetic order, free from relaxations. The magnetic easy axis is in the plane, but along @110# that means across the stripes. This cross magnetization induces ferromagnetic dipolar coupling between the spin blocks in adjacent stripes, which are preformed by exchange interactions. The resulting superferromagnetic phase transition is therefore driven by dipolar interactions. @S0163-1829~98!52002-4#