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High-pressure high-temperature (HPHT) crystalline monosulfide solid solution (Mss) phases (FexNi1−xS, x = 0.90, 0.75, 0.50, 0.25), troilite (FeS I), and α-NiS of the Fe-Ni-S system were synthesized at 7 GPa and 900–1550 °C. The structural parameters of the obtained phases were refined by XRD using the Rietveld method. Factor group analysis revealed the number of active Raman modes for FeS I and α-NiS. Raman spectra of troilite, α-NiS, and Mss phases were obtained. It was shown that the Raman spectra of Mss phases and α-NiS have a similar topology. The Raman spectra of the experimental phases in the Fe-Ni-S system were analyzed with non-negative matrix factorization, which provided a meaningful concentration dependence of the spectral patterns. The spectral components were assigned to the FeS I and α-NiS structures. The structural and spectroscopic studies show linear dependencies of unit cell parameters and spectral components on composition and confirm the existence of a series of monosulfide solid solution FexNi1−xS. [ABSTRACT FROM AUTHOR]

A constraint g A 2 ≤ 4.5 × 10 − 24 (g 2 + 1 / λ A 2 ) on the constant gA of a new short-range (spin—orbit) interaction between nucleons, which is due to the exchange by a light spin-1 boson with the mass mA = ħ/λAc, has been obtained from experimental data on the transmission of neutrons through a noncentrosymmetric perfect crystal near the Bragg reflection characterized by the reciprocal lattice vector g. This constraint is the best in the interaction radius range λA = 10−12−10−5 m. [ABSTRACT FROM AUTHOR]

The spatial splitting of an unpolarized neutron beam into two spin components in an inhomogeneous magnetic field (an analog of the Stern-Gerlach experiment) with small gradients has been measured at the Laue diffraction in a crystal and Bragg angles θB = (78–82)° close to a right one. The spatial splitting of the beam at a path length of 21.8 cm has reached (4.1 ± 0.1) cm (at a maximum gradient of 1.5 G/cm and a diffraction angle of 82°). In the absence of the crystal, the splitting would be ∼ 3.8 × 10−7 cm at the same distance and gradient. The experimental enhancement coefficient is ∼ 105 tan2 θB, which is consistent with the theory. [ABSTRACT FROM AUTHOR]

The effect of neutron spin rotation at Laue diffraction in a weakly deformed neutron-transparent noncentrosymmetric crystal has been described theoretically and studied experimentally. The effect is due to the bending of a Kato trajectory of the neutron in the deformed crystal. At a certain type of deformation, one of two neutron waves excited at Laue diffraction, which propagate in opposite crystal fields in the crystal with no center of symmetry, leaves the crystal. As a result, the spin of the remaining neutron wave is rotated by a certain angle with respect to initial direction due to the interaction of the magnetic moment of a moving neutron with the crystalline electric field. This effect is absent in an undeformed perfect crystal, where only the depolarization of a beam occurs because both waves in opposite electric fields have the same amplitude. A method has been developed for controlled deforming the perfect single crystal by creating a temperature gradient in it. Thereby, a new possibility of measuring electric fields acting on a neutron in noncentrosymmetric crystals, as well as a method of controlling these fields in experiments on studying the fundamental properties of the neutron, has been implemented. [ABSTRACT FROM AUTHOR]

Diffraction enhancement of small effects affecting a neutron undergoing Laue diffraction at Bragg angles θB close to 90° is predicted and experimentally observed. The enhancement is due to the delay of the neutron inside the crystal during diffraction and is proportional to tan2 θB. As a result, the diffraction enhancement factor may be as large as ∼108–109. On this basis, a new method is proposed for searching for the electric charge of the neutron and for measuring the ratio of its inertial mass m i to the gravitational mass m G. It is shown that the accuracy of the neutron charge measurement can be improved by more than two orders of magnitude in relation to the present-day accuracy and that the ratio m i/ m G can be measured to an precision of σ( m i/ m G) ∼ 10−6. [ABSTRACT FROM AUTHOR]

Detailed study of a neutron Laue diffraction in a noncentrosymmetric crystal was carried out using a prototype of the experimental setup to measure the neutron electric dipole moment (nEDM) by Laue diffraction method (LDM). A new kind of spin rotation effect was observed for the first time. We attribute this effect to a difference of the two Bloch waves amplitudes in the crystal, which is caused by the presence of the definite small crystal deformation. In a revised scheme of the experiment, this effect could be exploited for a purposeful manipulation of the Bloch waves. [ABSTRACT FROM AUTHOR]

An essential magnification of an external force acting on a diffracting neutron for the Bragg angles θB close to the right one is observed. Any external action (caused by either crystal deformation or external force affected the neutron) results in a bend of the so called “Kato trajectories” inside the crystal and, for the case of a finite crystal, gives considerable variation of the intensities of both diffracted neutron beams (direct and reflected). It is shown that the magnification factor is proportional to tan2 (θb) and can reach (102−103) for Bragg angles surfficiently close to 90°. [ABSTRACT FROM AUTHOR]

The article focuses on in-plane hyperbolic polaritons in van der Waals crystals with tailored infrared nanoantennas. Topics include the phonon polaritons (PhPs) light coupled to lattice vibrations with in-plane hyperbolic dispersion exhibit raylike propagation with large wave vectors and enhanced density of optical states along certain directions on a surface, and the demonstrate focusing of in-plane hyperbolic PhPs propagating along thin slabs.