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Neutron reflectometry is a method for measuring the spatial profile of the neutron interaction potential with the medium. The interaction potential is the sum of neutron interaction potentials with separate isotopes of the medium. To determine the neutron interaction potential with the structure units, secondary radiation is simultaneously registered with neutrons. Channels for registering secondary radiation of charged particles, gamma rays and neutrons, having experienced spin flip, have been developed on the REMUR spectrometer of the IBR-2 reactor in Dubna (Russia). The necessity of registering secondary radiation in neutron reflectometry is justified, a method developed for measuring secondary radiation is described and the results of testing channels for registering secondary radiation on the REMUR spectrometer are presented in the paper.

The role of size effects in the formation of the magnetic structure of Dy and Ho thin films in absence of epitaxial strain is studied in this work. It was found that, for Dy in the temperature range between the Néel temperature and the Curie temperature of bulk Dy and, for Ho, in the temperature range between the Néel temperature and the temperature of phase transition into the conic phase, the temperature dependences of the period of magnetic helicoid in the bulk and film metals are similar. The character of the transition into the ferromagnetic phase in the Dy films changes at lower temperatures, and the transition into the commensurable conic phase in the Ho films is suppressed. This is explained exclusively by the influence of dimensional effects. © 2021, Pleiades Publishing, Ltd. Synthesis of samples and magnetometric measurements were performed at the Center of the Collaborative Access, Institute of Metal Physics, Ural Branch, Russian Academy of Sciences. Experimental data obtained with the REMUR reflectometer were transformed from the instrumental coordinate system into the reciprocal space coordinate system using Överlåtaren software []. This study was supported by the Russian Foundation for Basic Research, project no. 19-32-90007.

We have used spin-polarized neutron reflectometry to investigate the magnetization profile of superlattices composed of ferromagnetic Gd and superconducting Nb layers. We have observed a partial suppression of ferromagnetic (F) order of Gd layers in [Gd($d_F$)/Nb(25nm)]$_{12}$ superlattices below the superconducting (S) transition of the Nb layers. The amplitude of the suppression decreases with increasing $d_F$. By analyzing the neutron spin asymmetry we conclude that the observed effect has an electromagnetic origin - the proximity-coupled S layers screen out the external magnetic field and thus suppress the F response of the Gd layers inside the structure. Our investigation demonstrates the considerable influence of electromagnetic effects on the magnetic properties of S/F systems.

Neutron reflectometry is a method for measuring of the spatial dependence (profile) of the potential interaction between neutron and medium. At interface of media the interaction potential is the sum of the elements potentials. For definition of potentials of separate elements (isotopes) a secondary radiation is recorded. Recording channels of secondary radiation are created on spectrometer REMUR at pulsed reactor IBR-2 in Dubna (Russia). The results for testing of the channels are reported and perspectives of reflectometry with registration of secondary radiation are discussed