1,208 research outputs found
Magnetic Phase Control in Monolayer Films by Substrate Tuning
We propose to tailor exchange interactions in magnetic monolayer films by
tuning the adjacent non-magnetic substrate. As an example, we demonstrate a
ferromagnetic-antiferromagnetic phase transition for one monolayer Fe on a
Ta(x)W(1-x)(001) surface as a function of the Ta concentration. At the critical
Ta concentration, the nearest-neighbor exchange interaction is small and the
magnetic phase space is dramatically broadened. Complex magnetic order such as
spin-spirals, multiple-Q, or even disordered local moment states can occur,
offering the possibility to store information in terms of ferromagnetic dots in
an otherwise zero-magnetization state matrix.Comment: after minor changes, 5 pages, 5 figures, revtex
Magnetism of mixed quaternary Heusler alloys: (Ni,T)MnSn (T=Cu,Pd) as a case study
The electronic properties, exchange interactions, finite-temperature
magnetism, and transport properties of random quaternary Heusler NiMnSn
alloys doped with Cu- and Pd-atoms are studied theoretically by means of {\it
ab initio} calculations over the entire range of dopant concentrations. While
the magnetic moments are only weakly dependent on the alloy composition, the
Curie temperatures exhibit strongly non-linear behavior with respect to
Cu-doping in contrast with an almost linear concentration dependence in the
case of Pd-doping. The present parameter-free theory agrees qualitatively and
also reasonably well quantitatively with the available experimental results. An
analysis of exchange interactions is provided for a deeper understanding of the
problem. The dopant atoms perturb electronic structure close to the Fermi
energy only weakly and the residual resistivity thus obeys a simple Nordheim
rule. The dominating contribution to the temperature-dependent resistivity is
due to thermodynamical fluctuations originating from the spin-disorder, which,
according to our calculations, can be described successfully via the disordered
local moments model. Results based on this model agree fairly well with the
measured values of spin-disorder induced resistivity.Comment: 13 pages, 13 figure
How Skill Requirements Affect the Likelihood of Recruitment of Older Workers in Poland: The Indirect Role of Age Stereotypes
This article analyses the role of age stereotypes in the employability of older people. Unlike in existing studies, we shift emphasis from a direct consideration of stereotypes, focusing instead on skill requirements during recruitment. Using five waves of an employer survey from Poland, we assess how the likelihood of recruiting people over 50 years old depends on the skill requirements of the post. This study uses a real-life framework by referring to existing vacancies and actual requirements that reflect labour demands at the scale of an entire national labour market. The results suggest that some requirements lead to age bias during recruitment, and the chances of an older candidate being hired are especially hindered in jobs requiring computer, physical, social, creative and training skills. By illustrating an indirect link between age stereotypes and age discrimination, this study contributes to an understanding of the mechanisms that reduce employability of older people
Spin-injection through an Fe/InAs Interface
The spin-dependence of the interface resistance between ferromagnetic Fe and
InAs is calculated from first-principles for specular and disordered (001)
interfaces. Because of the symmetry mismatch in the minority-spin channel, the
specular interface acts as an efficient spin filter with a transmitted current
polarisation between 98 an 89%.
The resistance of a specular interface in the diffusive regime is comparable
to the resistance of a few microns of bulk InAs.
Symmetry-breaking arising from interface disorder reduces the spin asymmetry
substantially and we conclude that efficient spin injection from Fe into InAs
can only be realized using high quality epitaxial interfaces.Comment: 4 pages, 4 figure
Interface resistance of disordered magnetic multilayers
We study the effect of interface disorder on the spin-dependent interface
resistances of Co/Cu, Fe/Cr and Au/Ag multilayers using a newly developed
method for calculating transmission matrices from first-principles. The
efficient implementation using tight-binding linear-muffin-tin orbitals allows
us to model interface disorder using large lateral supercells whereby specular
and diffuse scattering are treated on an equal footing. Without introducing any
free parameters, quantitative agreement with experiment is obtained. We predict
that disorder {\it reduces} the majority-spin interface resistance of
Fe/Cr(100) multilayers by a factor 3.Comment: 5 pages, 2 figures, submitted to PR
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