•RXMR can be used to analyze buried magnetic interfaces.•In Co90Fe10/Ni67Cu33 junctions Ni magnetic moments are switchable in unison with those in Co90Fe10.•In Co90Fe10/Ni67Cu33/Ni80Fe20 stacks the ...Ni67Cu33 spacer is coupled stronger to Co90Fe10 than to Ni80Fe20.
It is of interest to explore magnetic configurations and phase transitions at the interfaces between different magnetic materials by employing nondestructive and element-specific methods such as resonant X-ray magnetic reflectometry (RXMR). Using RXMR, we have measured element-specific hysteresis loops of a layered stack of TaO(15 nm)/Ir20Mn80(25 nm)/Co90Fe10(3 nm)/Ni67Cu33(10 nm)/Ni80Fe20(10 nm)/quartz substrate at the Fe и Ni absorption edges. The goal here is to highlight the contribution of the weakly ferromagnetic Ni67Cu33 spacer in this system where the spacer is sandwiched between strong ferromagnets, Ni80Fe20 and Co90Fe10. We find two kinds of the spacer effects on magnetization switching in the system. One of them is that switching of the Co90Fe10 magnetization displays at the Ni absorption edge. Such a behavior of the magnetic reflectivity results from strong exchange coupling of the spacer to the Co90Fe10 surrounding across the interface between them. Another one is that temperature variation around the Curie point of the spacer (TC ≈ 240 K) provides a stronger change of the magnetic contrast at the Ni80Fe20/Ni67Cu33 interface than that at the Co90Fe10/Ni67Cu33 one. This feature indicates weaker exchange coupling across the Ni80Fe20/Ni67Cu33 interface.
The application of the method of phase-amplitude functions to the calculation of neutron-transmission processes in layered media containing highly absorbent elements is described. This method allows ...us to simultaneously calculate the reflection, transmission and absorption coefficients for neutrons. It requires less computing resources than other algorithms. A generalization of the method to matrix equations used in polarized neutron reflectometry is also presented. Examples of calculations of various characteristics of neutron transmission for layered resonator-type systems with a potential well are given.
Polarized neutron reflectometry is used to study Dy/Gd superlattices with different ratios of Dy- and Gd-layer thicknesses: 1 : 1, 2 : 1, and 3 : 1. It is experimentally shown that the formation of ...helicoidal magnetic ordering in Dy layers with a period incommensurate with that of the superlattice manifests itself in the appearance of a magnetic-superlattice reflection, which is forbidden due to equality of the thicknesses of alternating Dy and Gd layers with a ratio of 1 : 1. Otherwise, the formation of helicoidal magnetic ordering has little effect on the shape of the neutron-reflectometry curves. Thus, optimization of the structure of rare-earth superlattices for the neutron-reflectometry experiment makes it possible to detect helicoidal magnetic ordering in superlattices with a period incommensurate with the structural superlattice ordering.
•The experimental results of magnetothermal properties in Dy films and their comparison with the theoretical modeling of the same data are presented.•Dy induces thermal hysteresis in specific applied ...magnetic fields.•The ferromagnetic phase is favored in the heating process.•The helimagnetic phase is favored in the cooling process.
We present in this paper the experimental results of magnetothermal properties in Dy films and their comparison with the theoretical modeling of the same data. We consider the temperature interval between 80 and 200 K, where Dy is ferromagnetic in low-temperature regions and helimagnetic for high temperatures. Our findings show that due to different phases in the considered temperature interval, the Dy induces thermal hysteresis in specific applied fields. We found that the ferromagnetic phase is favored in the heating process, and in the cooling process, the helimagnetic phase is favored.
•Magnetic H-T phase diagram of a Fe/Gd ferrimagnetic superlattice is obtained.•Collinear, twisted and surface twist magnetic states are identified.•Two spectral branches of ferromagnetic resonance ...are observed.•The observed modes correspond to different types of non-uniform precession in Gd.
Static and dynamic magnetic properties of a ferrimagnetic Fe(35Å)/Gd(50Å)12 superlattice were investigated in a wide 4–300 K temperature range using magneto-optical Kerr effect (MOKE) and ferromagnetic resonance (FMR) techniques. The multilayer structure was sputtered on a transparent glass substrate which made it possible to perform MOKE measurements on both Fe and Gd terminated sides of the superlattice. These experiments allowed us to detect a transition between field-aligned and canted magnetic states on both sides of the film and to distinguish between the bulk and surface twisted phases of the superlattice. As a result, the experimental H-T magnetic phase diagram of the system was obtained. FMR studies at frequencies 7–36 GHz demonstrated a complex evolution of absorption spectra as temperature decreased from room down to 4 K. Two spectral branches were detected in the sample. Theoretical simulations show that the observed spectral branches correspond to different types of inhomogeneous resonance modes in the multilayer with non-uniform magnetization precession inside Gd layers.
Systematic data on the structural state and magnetic properties of films belonging to the binary Dy
100 –
x
Co
x
system have been measured within broad ranges of compositions (0 ≤
x
< 85), ...temperatures (5‒300 K), and magnetic fields (0–70 kOe). It was found that in the absence of magnetic moment on Co atoms (
x
≤ 50), the films are in an asperomagnetic state, in which a considerable and nonmonotonical concentration change in the principal magnetic characteristics is observed. In the region of
x
> 50, the films have a sperimagnetic structure. It has been shown that the quantitative description of spontaneous magnetization in such a state can be obtained in the molecular field model.
Layered nanoheterostructure Fe|MgO|Cr|MgO|Fe is an artificial ferromagnetic material in which exchange interaction of magnetic moments in the iron layers through intermediate dielectric and metal ...layers can lead to magnetic configurations which do not appear in well-studied systems Fe|MgO|Fe and Fe|Cr|Fe. In this work correlations of the structural and magnetic properties of layered nanoheterostructures Fe(10 nm)|MgO(1.5 nm)|Cr(
t
nm)|MgO(1.5 nm)|Fe(7 nm) (with the thickness
t
being 0.9 and 1.8 nm) were studied. Structural studies made using high-resolution X-ray diffractometry and reflectometry proved the formation of a texturized structure and revealed its prominent layered character with clear interfaces between the layers.
The structure and magnetic properties of thin polycrystalline films of Co
100 –
x
W
x
(0 ≤
x
≤ 30) deposited by magnetron sputtering on glass substrates are investigated including those containing ...buffer layers of Ta, W, and Ru. It is found that films of pure Co are non-single-phase and contain hcp and fcc crystalline modifications. Doping leads to an increase in the concentration of the fcc phase and an enhancement of the texture of the (111) type, and subsequently to the amorphization of the films. The buffer layers influence to a certain extent on the depth and concentration localization of these transformations. A characteristic feature of the magnetism of Co–W films is a significant perpendicular component in the macroscopic magnetic anisotropy, which leads to a “supercritical” magnetic state. It is shown that its source is the textured fcc phase, the crystalline anisotropy of which is enhanced as a result of doping of cobalt with tungsten.
The article is dedicated to reveling the reason of unusual magnetic properties, found in one of Co/Dy periodic multilayer systems with different Co/Dy layer thickness by X-Ray reflectivity, ...scanning/transmission electron microscopy together with energy dispersive X-Ray microanalysis. Magnetic measurements did not demonstrate any peculiarities in the system with thinner Co/Dy layer thickness. However, the system with thicker layers demonstrated an anomalous behavior of the perpendicular magnetic anisotropy. Based on X-Ray reflectivity measurements, it was found that the polarizability value in the system with thicker Co/Dy layer was very high and related to glassy intermetallic DyCo2 compound formation. Electron microscopy and microanalysis data also indicated the presence of glassy intermetallic DyCo2 layers, which could be responsible for the peculiar magnetic behavior. The relation between magnetic properties and microstructure was revealed.
•Thick Co/Dy periodic multilayer system demonstrates an anomalous perpendicular magnetic anisotropy.•Thin Co/Dy system does not show any peculiarities.•Polarizability of thick Co/Dy system is high and indicates glassy DyCo2.•Intermixing and formation of partially glassy layers occur.
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