Search

Interface engineering in complex oxide superlattices is a growing field, enabling manipulation of the exceptional properties of these materials, and also providing access to new phases and emergent physical phenomena. Here we demonstrate how interfacial interactions can induce a complex charge and spin structure in a bulk paramagnetic material. We investigate a superlattice (SLs) consisting of paramagnetic LaNiO3 (LNO) and highly spin-polarized ferromagnetic La2/3Ca1/3MnO3 (LCMO), grown on SrTiO3 (001) substrate. We observed emerging magnetism in LNO through an exchange bias mechanism at the interfaces in X-ray resonant magnetic reflectivity. We find non-symmetric interface induced magnetization profiles in LNO and LCMO which we relate to a periodic complex charge and spin superstructure. High resolution scanning transmission electron microscopy images reveal that the upper and lower interfaces exhibit no significant structural variations. The different long range magnetic order emerging in LNO layers demonstrates the enormous potential of interfacial reconstruction as a tool for tailored electronic properties.

The interface between the insulators LaAlO$_3$ and SrTiO$_3$ accommodates a two-dimensional electron liquid (2DEL) -- a high mobility electron system exhibiting superconductivity as well as indications of magnetism and correlations. While this flagship oxide heterostructure shows promise for electronics applications, the origin and microscopic properties of the 2DEL remain unclear. The uncertainty remains in part because the electronic structures of such nanoscale buried interfaces are difficult to probe, and is compounded by the variable presence of oxygen vacancies and coexistence of both localized and delocalized charges. These various complications have precluded decisive tests of intrinsic electronic and orbital reconstruction at this interface. Here we overcome prior difficulties by developing an interface analysis based on the inherently interface-sensitive resonant x-ray reflectometry. We discover a high charge density of 0.5 electrons per interfacial unit cell for samples above the critical LaAlO$_3$ thickness, and extract the depth dependence of both the orbital and electronic reconstructions near the buried interface. We find that the majority of the reconstruction phenomena are confined to within 2 unit cells of the interface, and we quantify how oxygen vacancies significantly affect the electronic system. Our results provide strong support for the existence of polarity induced electronic reconstruction, clearly separating its effects from those of oxygen vacancies., Accepted in Physical Review Materials

Knowledge of crayfish species’ life history traits is vital to their conservation and management. Fecundity is one trait that is a likely indicator of extinction risk and potential invasiveness. Fecundity-related data are lacking for the imperiled St. Francis River crayfish (Faxonius quadruncus) that is declining in the presence of the invasive woodland crayfish (Faxonius hylas). We sampled ovigerous females in three populations each of F. quadruncus and invasive F. hylas in Missouri (USA) Ozarks streams during April 2014 to compare fecundity and egg size between the two species. Differences in fecundity-related traits existed among populations of F. quadruncus, but no differences existed between the species. Results for both species were well within the ranges reported for other Faxonius species, but likely reflect small sample sizes rather than the entirety of each species. We also investigated the utility of field versus laboratory fecundity measures and found that field egg counts on live females varied among observers and also underestimated laboratory counts by an average of 22%. We provide a linear equation that can serve as a correction adjustment for field pleopodal fecundity estimates on live females to avoid specimen sacrifice during future monitoring of these species.

Magnetic ordering phenomena have a profound influence on the macroscopic properties of correlated-electron materials, but their realistic prediction remains a formidable challenge. An archetypical example is the ternary nickel oxide system RNiO3 (R = rare earth), where the period-four magnetic order with proposals of collinear and non-collinear structures and the amplitude of magnetic moments on different Ni sublattices have been subjects of debate for decades. Here we introduce an elementary model system - NdNiO3 slabs embedded in a non-magnetic NdGaO3 matrix - and use polarized resonant x-ray scattering (RXS) to show that both collinear and non-collinear magnetic structures can be realized, depending on the slab thickness. The crossover between both spin structures is correctly predicted by density functional theory and can be qualitatively understood in a low-energy spin model. We further demonstrate that the amplitude ratio of magnetic moments in neighboring NiO6 octahedra can be accurately determined by RXS in combination with a correlated double cluster model. Targeted synthesis of model systems with controlled thickness and synergistic application of polarized RXS and ab-initio theory thus provide new perspectives for research on complex magnetism, in analogy to two-dimensional materials created by exfoliation., This is the accepted version of the manuscript. The revised manuscript according to peer reviews was published online in Nature Physics on July 23, 2018

Thickness driven electronic phase transitions are broadly observed in different types of functional perovskite heterostructures. However, uncertainty remains whether these effects are solely due to spatial confinement, broken symmetry or rather to a change of structure with varying film thickness. Here, we present direct evidence for the relaxation of oxygen 2p and Mn 3d orbital (p-d) hybridization coupled to the layer dependent octahedral tilts within a La2/3Sr1/3MnO3 film driven by interfacial octahedral coupling. An enhanced Curie temperature is achieved by reducing the octahedral tilting via interface structure engineering. Atomically resolved lattice, electronic and magnetic structures together with X-ray absorption spectroscopy demonstrate the central role of thickness dependent p-d hybridization in the widely observed dimensionality effects present in correlated oxide heterostructures., Accepted by Adv. Funct. Mater

Combining dissimilar transition metal oxides (TMOs) into artificial heterostructures enables to create electronic interface systems with new electronic properties that do not exist in bulk. A detailed understanding of how such interfaces can be used to tailor physical properties requires characterization techniques capable to yield interface sensitive spectroscopic information with monolayer resolution. In this regard resonant x-ray reflectivity (RXR) provides a unique experimental tool to achieve exactly this. It yields the element specific electronic depth profiles in a non-destructive manner. Here, using a YBa2Cu3O7−δ (YBCO) thin film, we demonstrate that RXR is further capable to deliver site selectivity. By applying a new analysis scheme to RXR, which takes the atomic structure of the material into account, together with information of the local charge anisotropy of the resonant ions, we obtained spectroscopic information from the different Cu sites (e.g., chain and plane) throughout the film profile. While most of the film behaves bulk-like, we observe that the Cu-chains at the surface show characteristics of electron doping, whereas the Cu-planes closest to the surface exhibit an orbital reconstruction similar to that observed at La1−x Ca x MnO3/YBCO interfaces.

Emergent phenomena in transition-metal-oxide heterostructures such as interface superconductivity and magnetism have been attributed to electronic reconstruction, which, however, is difficult to detect and characterise. Here we overcome the associated difficulties to simultaneously address the electronic degrees of freedom and distinguish interface from bulk effects by implementing a novel approach to resonant X-ray reflectivity (RXR). Our RXR study of the chemical and valance profiles along the polar (001) direction of a LaCoO3 film on NdGaO3 reveals a pronounced valence-state reconstruction from Co3+ in the bulk to Co2+ at the surface, with an areal density close to 0.5 Co2+ ions per unit cell. An identical film capped with polar (001) LaAlO3 maintains the Co3+ valence over its entire thickness. We interpret this as evidence for electronic reconstruction in the uncapped film, involving the transfer of 0.5e− per unit cell to the subsurface CoO2 layer at its LaO-terminated polar surface. A new experimental design affords insight into electronic reconstruction at the interface between oxides. A number of unexpected phenomena have been seen when one oxide meets another, with a two-dimensional electron gas in the SrTiO3/LaAlO3 system being a well-known example. The underpinning mechanism remains up for debate however: the transfer of electronic charge between interfaces has been suggested – termed ‘electronic reconstruction ’ – but an unambiguous demonstration has been hampered by experimental difficulties. An international team lead by Vladimir Hinkov from University of Wurzburg now applies elementspecific resonant x-ray reflectivity to study the LaCoO3/vacuum interface, demonstrating a change in Co valence state in LaCoO3 from 3+ in the bulk to 2+ at this interface. This data provides compelling experimental evidence for electronic reconstruction at oxide interfaces.

Using resonant magnetic diffraction at the Ni L_{2,3} edge in a LaNiO_{3} superlattice, we show that dynamical effects beyond the standard kinematic approximation can drastically modify the resonant scattering cross section. In particular, the combination of extinction and refraction convert maxima to minima in the azimuthal-angle dependence of the diffracted intensity, which is commonly used to determine orbital and magnetic structures by resonant x-ray diffraction. We provide a comprehensive theoretical description of these effects by numerically solving Maxwell's equations in three dimensions. The understanding and description of dynamical diffraction enhances the capabilities of resonant x-ray scattering as a probe of electronic ordering phenomena in solids.

On the basis of the theory of micromagnetism we have analytically calculated the nucleation and depinning fields of composite exchange coupled spring systems composed of soft and hard magnetic layers. The values of the critical fields sensitively depend on the thicknesses of the layers and determine the shape of the corresponding hysteresis loop. The quality of the analytical calculations is verified by numerical micromagnetic simulations.

In epitaxial thin film systems, the crystal structure and its symmetry deviate from the bulk counterpart due to various mechanisms such as epitaxial strain and interfacial structural coupling, which is accompanyed by a change in their properties. In perovskite materials, the crystal symmetry can be described by rotations of sixfold coordinated transition metal oxygen octahedra, which are found to be altered at interfaces. Here, it is unraveled how the local oxygen octahedral coupling at perovskite heterostructural interfaces strongly influences the domain structure and symmetry of the epitaxial films resulting in design rules to induce various structures in thin films using carefully selected combinations of substrate/buffer/film. Very interestingly it is discovered that these combinations lead to structure changes throughout the full thickness of the film. The results provide a deep insight into understanding the origin of induced structures in a perovskite heterostructure and an intelligent route to achieve unique functional properties.

We present a combined study of Ni $K$-edge resonant x-ray scattering and density functional calculations to probe and distinguish electronically driven ordering and lattice distortions in nickelate heterostructures. We demonstrate that due to the low crystal symmetry, contributions from structural distortions can contribute significantly to the energy-dependent Bragg peak intensities of a bond-ordered $NdNiO_3$ reference film. For a $LaNiO_{3}−LaAlO_{3}$ superlattice that exhibits magnetic order, we establish a rigorous upper bound on the bond-order parameter. We thus conclusively confirm predictions of a dominant spin density wave order parameter in metallic nickelates with a quasi-two-dimensional electronic structure.

Controlled in-plane rotation of the magnetic easy axis in manganite heterostructures by tailoring the interface oxygen network could allow the development of correlated oxide-based magnetic tunnelling junctions with non-collinear magnetization, with possible practical applications as miniaturized high-switching-speed magnetic random access memory (MRAM) devices. Here, we demonstrate how to manipulate magnetic and electronic anisotropic properties in manganite heterostructures by engineering the oxygen network on the unit-cell level. The strong oxygen octahedral coupling is found to transfer the octahedral rotation, present in the NdGaO3 (NGO) substrate, to the La2/3Sr1/3MnO3 (LSMO) film in the interface region. This causes an unexpected realignment of the magnetic easy axis along the short axis of the LSMO unit cell as well as the presence of a giant anisotropic transport in these ultrathin LSMO films. As a result we possess control of the lateral magnetic and electronic anisotropies by atomic-scale design of the oxygen octahedral rotation.

We studied the electronic and magnetic dynamics of ferromagnetic insulating BaFeO3 thin films by using pump-probe time-resolved resonant x-ray reflectivity at the Fe 2p edge. By changing the excitation density, we found two distinctly different types of demagnetization with a clear threshold behavior. We assigned the demagnetization change from slow (~ 150 ps) to fast (< 70 ps) to a transition into a metallic state induced by laser excitation. These results provide a novel approach for locally tuning magnetic dynamics. In analogy to heat assisted magnetic recording, metallization can locally tune the susceptibility for magnetic manipulation, allowing to spatially encode magnetic information., 5 pages, 4 figures

We have analytically calculated and compared the total magnetic energies of remanent magnetization states of hollow particles to find conditions for single-domain behavior. The size of the particles and the thickness of the spheroidal shell have been systematically varied for different hard and soft magnetic materials and the corresponding phase diagrams of the lowest-energy configurations are derived.

The discovery of two-dimensional electron gases (2DEGs) at the interface between two insulating complex oxides, such as LaAlO3 (LAO) or gamma-Al2O3 (GAO) epitaxially grown on SrTiO3 (STO) 1,2, provides an opportunity for developing all-oxide electronic devices3,4. These 2DEGs at complex oxide interfaces involve many-body interactions and give rise to a rich set of phenomena5, for example, superconductivity6, magnetism7,8, tunable metal-insulator transitions9, and phase separation10. However, large enhancement of the interfacial electron mobility remains a major and long-standing challenge for fundamental as well as applied research of complex oxides11-15. Here, we inserted a single unit cell insulating layer of polar La1-xSrxMnO3 (x=0, 1/8, and 1/3) at the interface between disordered LaAlO3 and crystalline SrTiO3 created at room temperature. We find that the electron mobility of the interfacial 2DEG is enhanced by more than two orders of magnitude. Our in-situ and resonant x-ray spectroscopic in addition to transmission electron microscopy results indicate that the manganite layer undergoes unambiguous electronic reconstruction and leads to modulation doping of such atomically engineered complex oxide heterointerfaces. At low temperatures, the modulation-doped 2DEG exhibits clear Shubnikov-de Haas oscillations and the initial manifestation of the quantum Hall effect, demonstrating an unprecedented high-mobility and low electron density oxide 2DEG system. These findings open new avenues for oxide electronics., Comment: 29 pages, 5 figures, Accepted for publication in Nature Materials

Measuring the magnetic configuration at complex buried layers and interfaces is an important task, which requires especially a non-destructive probing technique. X-ray resonant magnetic reflectometry (XRMR) combines the non-destructive depth profiling potential of x-ray reflectometry with the excellent sensitivity for magnetic phenomena, utilizing the x-ray magnetic circular dichroism effect. It provides the magnetic spatial distribution with a precision down to the angstrom scale, combined with element and symmetry specificity, sub-monolayer sensitivity, and the possible separation of spin and orbital magnetic moments. This review provides an overview to the XRMR technique in a tutorial way. We focus on the introduction to the theory, measurement types, and data simulation. We provide related experimental examples and show selected applications.

Using a recently developed impurity solver we exemplify how dynamical mean-field theory captures band excitations, resonances, edge singularities and excitons in core level x-ray absorption spectroscopy (XAS) and core level photo electron spectroscopy (cPES) on metals, correlated metals and Mott insulators. Comparing XAS at different values of the core-valence interaction shows how the quasiparticle peak in the absence of core-valence interactions evolves into a resonance of similar shape, but different origin. Whereas XAS is rather insensitive to the metal insulator transition, cPES can be used, due to nonlocal screening, to measure the amount of local charge fluctuation.

Too often, software developers follow inefficient methods and procedures. The Personal Software Process, developed by Watts Humphrey at the Software Engineering Institute, provides software engineers with a methodology for consistently and efficiently developing high quality products. The value of PSP has been shown in three case studies-three industrial software groups have used PSP and have collected data to show its effectiveness. They are: Advanced Information Services, Inc., Motorola Paging Products Group, and Union Switch and Signal Inc. Each has trained several groups of engineers and measured the results of several projects that used PSP methods. In all cases, the projects were part of the companies' normal operations and not designed for this study. The three companies offered a variety of situations useful for demonstrating the versatility of PSP. The projects at Motorola and US&S involved software maintenance and enhancement, while those at AIS involved new product development and enhancement. Among the companies, application areas included commercial data processing, internal manufacturing support, communications product support, and real time process control. Work was done in C or C++.

A combined analysis of x-ray absorption and resonant reflectivity data was used to obtain the orbital polarization profiles of superlattices composed of four-unit-cell-thick layers of metallic LaNiO${}_{3}$ and layers of insulating $RX$O${}_{3}$ ($R=\text{La}$, Gd, Dy and $X=\text{Al}$, Ga, Sc), grown on substrates that impose either compressive or tensile strain. This superlattice geometry allowed us to partly separate the influence of epitaxial strain from interfacial effects controlled by the chemical composition of the insulating blocking layers. Our quantitative analysis reveals orbital polarizations up to 25$%$. We further show that strain is the most effective control parameter, whereas the influence of the chemical composition of the blocking layers is comparatively small.

Epitaxial strain imposed in complex oxide thin films by heteroepitaxy is recognized as a powerful tool for identifying new properties and exploring the vast potential of materials performance. A particular example is LaCoO3, a zero spin, nonmagnetic material in the bulk, whose strong ferromagnetism in a thin film remains enigmatic despite a decade of intense research. Here, we use scanning transmission electron microscopy complemented by X-ray and optical spectroscopy to study LaCoO3 epitaxial thin films under different strain states. We observed an unconventional strain relaxation behavior resulting in stripe-like, lattice modulated patterns, which did not involve uncontrolled misfit dislocations or other defects. The modulation entails the formation of ferromagnetically ordered sheets comprising intermediate or high spin Co3+, thus offering an unambiguous description for the exotic magnetism found in epitaxially strained LaCoO3 films. This observation provides a novel route to tailoring the electronic and magnetic properties of functional oxide heterostructures., 19 pages, 6 figures, including Supporting Information; Nano Letters published online (2012)

Using neutron reflectometry and resonant x-ray techniques we studied the magnetic proximity effect (MPE) in superlattices composed of superconducting ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7}$ and ferromagnetic-metallic ${\mathrm{La}}_{0.67}{\mathrm{Ca}}_{0.33}{\mathrm{MnO}}_{3}$ or ferromagnetic-insulating ${\mathrm{LaMnO}}_{3+\ensuremath{\delta}}$. We find that the MPE strongly depends on the electronic state of the manganite layers, being pronounced for the ferromagnetic-metallic ${\mathrm{La}}_{0.67}{\mathrm{Ca}}_{0.33}{\mathrm{MnO}}_{3}$ and almost absent for ferromagnetic-insulating ${\mathrm{LaMnO}}_{3+\ensuremath{\delta}}$. We also detail the change of the magnetic depth profile due to the MPE and provide evidence for its intrinsic nature.

Vineatrol(®) 30 is a grapevine-shoot extract, which contains resveratrol as well as considerable amounts of so-called resveratrol oligomers such as hopeaphenol and r2-viniferin. In this study, we analysed whether the two above-mentioned resveratrol oligomers were able to inhibit the growth of the canine glioblastoma cell line D-GBM and the canine histiocytic sarcoma cell line DH82, compared their potency to inhibit tumour cell growth with that of resveratrol and determined whether the induction of apoptosis via caspase 9 and 3/7 activation underlies the tumour cell growth-inhibiting effect of hopeaphenol and r2-viniferin. Vineatrol(®) 30, resveratrol, hopeaphenol and r2-viniferin inhibited the growth of D-GBM and DH82 cells in a concentration-dependent manner, whereby hopeaphenol and r2-viniferin were more potent than resveratrol itself in inhibiting the growth of the canine tumour cell lines. Moreover, the anti-proliferative effect of both resveratrol oligomers in D-GBM cells is based on their capacity to induce caspase 9 and 3/7 activation.

Using neutron reflectometry and resonant x-ray techniques we studied the magnetic proximity effect (MPE) in superlattices composed of superconducting YBa2Cu3O7 and ferromagnetic-metallic La0.67Ca0.33MnO3 or ferromagnetic-insulating LaMnO(3+δ). We find that the MPE strongly depends on the electronic state of the manganite layers, being pronounced for the ferromagnetic-metallic La0.67Ca0.33MnO3 and almost absent for ferromagnetic-insulating LaMnO(3+δ). We also detail the change of the magnetic depth profile due to the MPE and provide evidence for its intrinsic nature.

Epitaxial bilayers of ferromagnetic La2/3Ca1/3MnO3 (LCMO) and superconducting YBa2Cu3O7-d (YBCO) have been grown on single-crystalline SrTiO3 (STO) substrates by pulsed laser deposition. The Manganese magnetization profile across the FM layer has been determined with high spatial resolution at low temperatures by X-ray resonant magnetic reflectivity (XRMR). It is found that not only the adjacent superconductor but also the substrate underneath influences the magnetization of the LCMO film at the interfaces at low temperatures. Both effects can be investigated individually by XRMR.

The occupation of d orbitals controls the magnitude and anisotropy of the inter-atomic electron transfer in transition-metal oxides and hence exerts a key influence on their chemical bonding and physical properties. Atomic-scale modulations of the orbital occupation at surfaces and interfaces are believed to be responsible for massive variations of the magnetic and transport properties, but could not thus far be probed in a quantitative manner. Here we show that it is possible to derive quantitative, spatially resolved orbital polarization profiles from soft-X-ray reflectivity data, without resorting to model calculations. We demonstrate that the method is sensitive enough to resolve differences of ~3% in the occupation of Ni e(g) orbitals in adjacent atomic layers of a LaNiO(3)-LaAlO(3) superlattice, in good agreement with ab initio electronic-structure calculations. The possibility to quantitatively correlate theory and experiment on the atomic scale opens up many new perspectives for orbital physics in transition-metal oxides.

A bilayer exchange-bias system composed of Fe/MnPd is investigated using x-ray magnetic circular dichroism XMCD and soft x-ray resonant magnetic reflectometry XRMR. The absorption and XMCD data at the Fe L and Mn L edges are used to derive the optical and magneto-optical properties of the individual layers. Then the structural and magnetic depth profiles of the sample are obtained from XRMR. From reflectivity measurements at the Fe L and Mn L edges, a precise magnetic depth profiling of the interface region between the ferromagnet F and antiferromagnet AF was carried out. It reveals rotatable and pinned uncompensated Mn moments in the AF. By comparing the signs and magnitudes of the absorption, the relative coupling directions in the system are determined. It is found that rotatable Mn and the ferromagnetic Fe couple antiparallel. The pinned Mn moments are oriented antiferromagnetic to the neighboring rotatable Mn and ferromagnetic with respect to the Fe during the field cooling process.

The analysis of x-ray reflectivity data from artificial heterostructures usually relies on the homogeneity of optical properties of the constituent materials. However, when the x-ray energy is tuned to an absorption edge, this homogeneity no longer exists. Within the same material, spatial regions containing elements at resonance will have optical properties very different from regions without resonating sites. In this situation, models assuming homogeneous optical properties throughout the material can fail to describe the reflectivity adequately. As we show here, resonant soft x-ray reflectivity is sensitive to these variations, even though the wavelength is typically large as compared to the atomic distances over which the optical properties vary. We have therefore developed a scheme for analyzing resonant soft x-ray reflectivity data, which takes the atomic structure of a material into account by "slicing" it into atomic planes with characteristic optical properties. Using LaSrMnO4 as an example, we discuss both the theoretical and experimental implications of this approach. Our analysis not only allows to determine important structural information such as interface terminations and stacking of atomic layers, but also enables to extract depth-resolved spectroscopic information with atomic resolution, thus enhancing the capability of the technique to study emergent phenomena at surfaces and interfaces., Comment: Completely overhauled with respect to the previous version due to peer review

Although published reports indicate that collaboration between universities and industry can be beneficial to both, many companies are skeptical of such partnership because of the risk. This paper is a report on lessons learned and experiences gained, and results achieved thus far as the work is still in progress. Our efforts show that when there are shared and articulated goals with common expectations and consistent communication, positive results can be achieved. At the Motorola Paging Product Group (PPG), a team was organized to devise and implement a plan that will evaluate and incorporate effective personal software process (PSP) practices into Motorola PPG software development process. The team, a combination of industry practitioners and academic educators, first established a team process, then devised a plan and began implementation in order to achieve the stated goals.

Measuring the magnetic configuration at complex buried layers and interfaces is an important task, which requires especially a non-destructive probing technique. X-ray resonant magnetic reflectometry (XRMR) combines the non-destructive depth profiling potential of x-ray reflectometry with the excellent sensitivity for magnetic phenomena, utilizing the x-ray magnetic circular dichroism effect. It provides the magnetic spatial distribution with a precision down to the angstrom scale, combined with element and symmetry specificity, sub-monolayer sensitivity, and the possible separation of spin and orbital magnetic moments. This review provides an overview to the XRMR technique in a tutorial way. We focus on the introduction to the theory, measurement types, and data simulation. We provide related experimental examples and show selected applications.

The classification of psychiatry to date is governed firstly by psychopathological symptoms and syndromes in addition to factors of personal and family history. It succeeded for the first time after discovering the serotonin-shortage syndrome, to correlate the different psychopathological conditions with a biochemical disturbance, as the result of which a new indication orientation based on a functional target syndrom could come about in psychiatry.

Long-term thermal stability is crucial for magnetic nanoparticles in ultrahigh density magnetic recording. For ledge-type exchange-spring nanocomposites consisting of a hard magnetic L10-FePt part and a soft magnetic Fe part of more extended horizontal size, the minimum energy barriers for thermal reversal between equilibrium states of the hysteresis loops are determined using a nudged-elastic-band path approach. The field dependence of the energy barrier can be described approximately by power laws. It turns out that nanopatterns of isolated ledge-type L10-FePt/Fe composite elements or isolated L10-FePt nanodots covered by a thin Fe film are well-suited in realizing ultrahigh recording densities.

For exchange coupled composite particles composed of a soft and a hard magnetic layer, the minimum energy paths between equilibrium states of the hysteresis loops are calculated using a path approach based on the nudged elastic band method. From the minimum energy paths the energy barriers for thermal reversal are determined as a function of the applied magnetic field. The field dependence of the energy barrier can be described approximately by power laws. Until reaching the saddle point for thermal reversal a domain wall is nucleated and compressed to the width of a wall propagating through a hard magnetic reference particle.

By.focusing on very highly educated women, the present study serves to further test the comprehensiveness of role theory as an explanation of the complex relationship between female employment and marital adjustment. The data are from a sample of 663 women who received high-level graduate degrees from a large midwestern university between 1964 and 1974. Because females with high-level degrees expected to make use of their training and pursue their careers, it was thought that in this instance the marital adjustment qf working women would be higher than that fbr nonworking women. The findings are in the predicted direction. However, looking at the various regression equations, it appears that it is not employment status per se that is important in determining marital adjustment but rather the extent to which family experiences accommodate the wife's employment. Having a supportive husband seems to be a major factor, i.e., one who is willing to quit his job and move to advance the wife's career; one who does not insist that the wife quit her job and move to advance his career; and one who shares similar values and beliefs, especially about women's employment, as represented by educational homogamy. Freedom from childbearing responsibilities is also important.