Yu. N. Khaidukov

Magnetic non-collinear neutron wave resonator

Abstract Equations for the neutron reflection amplitude from a magnetic non-collinear wave resonator (NWR) are obtained. It is shown that resonances of the same reflection order of neutrons experiencing spin-flip (spin-flip neutrons) appear in pairs. Conditions, under which resonator square enhancement of the spin-flip neutron reflection intensity with respect to growth of the portion of scattered and absorbed neutrons takes place, are determined.

Coexistence of Superconductivity and Ferromagnetism in the Nb(500 Å)/Fe(39 Å)/(Si(34 Å)/Mo(34 Å)) 40 /Si Nanostructure

The results of polarized neutron reflectometry investigations of the magnetic state of the Nb(500 Å) superconductor-57Fe(39 Å) ferromagnet-Si(34 Å)/Mo(34 Å)]40 superconductor nanostructure in the temperature range 2–60 K in the magnetic field with a strength of 0.5 kOe are presented. A decrease in magnetization in an iron layer for the transition of Nb(500 Å) and [Si(34 Å)/Mo(34 A)]40 layers to the superconducting state has been found.

Formation mechanism, structure and adsorption characteristics of microporous nanocrystalline thin-film (V, Ti)-N-He composites

The main features of the formation of (V, Ti)-N-He thin films deposited under bombardment by mixed beams of high-energy N and He ions are studied. Their structural, phase, electrophysical, and adsorption characteristics are studied. The electron microscopy data proved that the structure of (V, Ti)-N-He compounds forms under the conditions of competition of several simultaneously occurring processes leading to the formation of a nanocrystalline structure that contains micropores with dimensions of 5 nm to 5 μm. The role of ion bombardment and gas adsorption from the residual atmosphere in forming porosity is discussed. The comparison of the Rutherford backscattering and profilometry data makes it possible to determine the value of the film porosity (27%). In the pressure range under study (up to 0.35 MPa), 600 cm3/g or more (7 wt %) of hydrogen was adsorbed. It is shown that pores accumulate the main portion of hydrogen; in this case, the amount of hydrogen depends not on the material composition, but on the microporous film structure and the composition of the gas medium in pores.

Features of the magnetic state of the layered Fe-V nanostructure of the superconductor-ferromagnet type

The magnetic state of the V(39 nm)/20 [V(3 nm)/Fe(3 nm)] nanostructure has been investigated by polarized neutron reflectometry in the temperature range from 1.6 to 30 K in magnetic fields from 0.2 to 15 kOe. The data obtained indicate that the superconductivity of vanadium layers may affect magnetic ordering both over the depth of the structure and in its plane.

Investigation of the ultrasonic wave influence on magnetic ordering in a 20 × [Fe(20 Å)/Cr(12 Å)]/MgO layered structure

A 20 × [Fe(20 Å)/Cr (12 Å)]/MgO structure excited by an ultrasonic wave was investigated by polarized neutron reflectometry. It was found that magnetic domains oscillate and their effective size decreases in weak magnetic fields. In close-to-saturation fields, a magnetic lattice is formed in the layered structure; the interplanar spacings in this lattice change with an increase in the field strength and as a result of the excitation of the structure by an ultrasonic wave.

Peculiarities of magnetic states in ferromagnet/superconductor heterostructures due to the proximity effects

The peculiarities of magnetic states in ferromagnet (F)/superconductor (S) heterostructures due to the proximity effects are investigated with the use of polarized neutron reflectometry. An anomalously strong reduction in the magnetization of the F layer due to superconductivity is observed in the S/F/S system. The dependence of the effects on an external magnetic field is studied for the first time. The enhanced neutron standing waves are used for registration of weak signals.