arXiv subjects

L. Deak

Publications and source records attributed to L. Deak.

3 recordsLinked to original sources

arXiv2014

Angular dependence, blackness and polarization effects in integral conversion electron Mössbauer spectroscopy

General expressions of the electron yield in (^{57})Fe integral conversion electron Mössbauer spectroscopy were derived depending on the angle of incidence of the (γ)-rays, on the source polarization and on the isotopic abundance of the source and the absober (blackness effects) using an exponential escape function of the electrons originating from all Mössbauer-resonance-related processes. The present approach provides a firm theoretical basis to determine the alignment and direction of magnetization in the absorber. The intensity formulae were justified by least squares fits of (α-^{57})Fe spectral intensities measured in linearly and elliptically polarized source and absorber geometries. The fits reproduce the experimentally set angles with high accuracy. Limits of the current approach and its relation to other, less complete treatments in the literature are discussed.

cond-mat.other↗

arXiv2009

Study of proximity effects in superconductor/ferromagnet interface using waveguide enhancement of neutron standing waves

This work is devoted to experimental study of influence of superconductivity (S) on ferromagnetism (FM) (inverse proximity effects) with the help of Polarized Neutron Reflectivity. Combining meausurements of specular and diffuse intensities it is possible to obtain full picture of magnetization change in S/FM layered systems like magnetization rotation, domain state formation, inducing of magnetization in S layer, etc. To increase weak magnetic signal we propose to use enhanced neutron standing wave regime (e.g. waveguides). In previous work we have made calculation to increase enhcanced factor. Here we present results of preparation sets of S/FM samples and attestation of their structural, magnetic, superconducting and neutron waveguide properties.

cond-mat.supr-con↗

arXiv2007

Perturbative Theory of Grazing-Incidence Diffuse Nuclear Resonant Scattering of Synchrotron Radiation

Theoretical description of off-specular grazing-incidence nuclear resonant scattering of synchrotron radiation (Synchrotron Mössbauer Reflectometry, SMR) is presented. The recently developed SMR, similarly to polarized neutron reflectometry (PNR), is an analytical tool for the determination of isotopic and magnetic structure of thin films and multilayers. It combines the sensitivity of Mössbauer spectroscopy to hyperfine interactions and the depth selectivity of x-ray reflectometry. Specular reflection provides information on the depth profile, while off-specular scattering on the lateral structure of scattering layers. Off-specular SMR and PNR intensity formulae of a rather general multilayer with different domains, based on a Distorted Incident-Wave Approximation (DIWA) are presented. The Distorted-Wave Born Approximation (DWBA) results are given in an Appendix. Physical and numerical implications, why using DIWA, are explained. The temporal character of SMR imposes specific differences between SMR and PNR. In order to reveal the limits of DIWA and to compare the two analytical methods, two-dimensional diffuse SMR and PNR maps of an antiferromagnetic multilayer are calculated and critically compared. Experimental '$ω-2θ$' SMR map of a periodic $[ \mathrm{Fe}/\mathrm{Cr}]_{20}$ multilayer is presented and compared with simulations by the present theory.

cond-mat.other↗