Double-spiral magnetic structure of the Fe/Cr multilayer revealed by nuclear resonance scattering

We have studied the magnetization depth profiles in a [57Fe(dFe)/Cr(dCr)]x30 multilayer with ultrathin Fe layers and nominal thickness of the chromium spacers dCr 2.0 nm using nuclear resonance scattering of synchrotron radiation. The presence of a broad pure-magnetic half-order (1/2) Bragg reflection has been detected at zero external field. The joint fit of the reflectivity curves and Mossbauer spectra of reflectivity measured near the critical angle and at the "magnetic" peak reveals that the magnetic structure of the multilayer is formed by two spirals, one in the odd and another one in the even iron layers, with the opposite signs of rotation. The double-spiral structure starts from the surface with the almost antiferromagnetic alignment of the adjacent Fe layers. The rotation of the two spirals leads to nearly ferromagnetic alignment of the two magnetic subsystems at some depth, where the sudden turn of the magnetic vectors by ~180 deg (spin-flop) appears, and both spirals start to rotate in opposite directions. The observation of this unusual double-spiral magnetic structure suggests that the unique properties of giant magneto-resistance devices can be further tailored using ultrathin magnetic layers.Comment: 9 pages, 3 figure

Deconvolving Instrumental and Intrinsic Broadening in Excited State X-ray Spectroscopies

Intrinsic and experimental mechanisms frequently lead to broadening of spectral features in excited-state spectroscopies. For example, intrinsic broadening occurs in x-ray absorption spectroscopy (XAS) measurements of heavy elements where the core-hole lifetime is very short. On the other hand, nonresonant x-ray Raman scattering (XRS) and other energy loss measurements are more limited by instrumental resolution. Here, we demonstrate that the Richardson-Lucy (RL) iterative algorithm provides a robust method for deconvolving instrumental and intrinsic resolutions from typical XAS and XRS data. For the K-edge XAS of Ag, we find nearly complete removal of ~9.3 eV FWHM broadening from the combined effects of the short core-hole lifetime and instrumental resolution. We are also able to remove nearly all instrumental broadening in an XRS measurement of diamond, with the resulting improved spectrum comparing favorably with prior soft x-ray XAS measurements. We present a practical methodology for implementing the RL algorithm to these problems, emphasizing the importance of testing for stability of the deconvolution process against noise amplification, perturbations in the initial spectra, and uncertainties in the core-hole lifetime.Comment: 35 pages, 13 figure

Проектирование системы электроснабжения производственной базы по обслуживанию нефтяной промышленности

В выпускной работе рассматривается система электроснабжения производственной базы по обслуживанию нефтяной промышленности. Объектом исследования является прокатно-ремонтный цех производственной базы по обслуживанию нефтяной промышленности. Цель работы: Разработка системы электроснабжения производственной базы по обслуживанию нефтяной промышленности и развитие способности решать технико-экономические вопросы при проектировании систем электроснабжения. В процессе исследования проводились расчеты электрических нагрузок прокатно-ремонтного цеха и предприятия в целом, методами коэффициента расчетной активной мощности и коэффициента спроса соответственно. Произведен выбор низковольтного оборудования прокатно-ремонтного цеха и высоковольтного оборудования главной понизительной подстанции.In the graduate qualification work, the system of power supplying production base for servicing the oil industry is considered. The object of the study is a hire and repair shop of the production base for servicing the oil industry. Purpose of work: development power supplying system production base for servicing the oil industry and development of the ability to solve technical and economic issues in the design of power supplying systems. In the process of the study, calculations were made of the electrical loads of the hire and repair shop and the enterprise as a whole, using the methods of the active power factor and the demand factor, respectively. A choice of low-voltage equipment of the hire and repair shop and high-voltage equipment of the main step-down substation were made

Nuclear resonance reflectivity from a [57Fe/Cr]30 multilayer with the Synchrotron Mössbauer Source

Mössbauer reflectivity spectra and nuclear resonance reflectivity (NRR) curves have been measured using the Synchrotron Mössbauer Source (SMS) for a [57Fe/Cr]30 periodic multilayer, characterized by the antiferromagnetic interlayer coupling between adjacent 57Fe layers. Specific features of the Mössbauer reflectivity spectra measured with π-polarized radiation of the SMS near the critical angle and at the 'magnetic' maximum on the NRR curve are analyzed. The variation of the ratio of lines in the Mössbauer reflectivity spectra and the change of the intensity of the 'magnetic' maximum under an applied external field has been used to reveal the transformation of the magnetic alignment in the investigated multilayer.Mössbauer reflectivity experiments performed using the Synchrotron Mössbauer Source at the ESRF demonstrate the high efficiency of such investigations for the analysis and understanding of multilayer structures and magnetization profiles. © International Union of Crystallography, 2018.Russian Foundation for Basic Research, RFBR: 15-02-01674-a, 15-02-01502-a, 16-02-00887-aRussian Academy of Sciences, RASFederal Agency for Scientific Organizations: 1.1.3.5, 01201463330Funding for this research was provided by the Russian Federal Agency for Scientific Organizations on the theme ‘Spin’ No. 01201463330 and by the Project No. 1.1.3.5. of the Program No. 32 of the Presidium of Russian Academy of Sciences, and the research was supported in part by the Russian Foundation for Basic Research (Grants No. 15-02-01674-a, No. 15-02-01502-a and No. 16-02-00887-a)