We discuss the interaction between a polarized neutron beam and chiral magnetism with emphasis on magnetic chirality. Without any loss of generality, we adopt a simple approach to formalism that pinpoints to the salient features of chiral magnetic scattering and can be easily used to plan and interpret experiments. We also discuss the unique information that can be derived on the topology of chiral magnetic correlations and consider the example of the skyrmion hosting system MnSi. This is one of the most simple realisations of chiral magnetism and at the same time a system, where the interaction between magnetic chirality and a polarized neutron beam is most clearly noticeable. In a next step we address the interplay between chiral magnetism and paramagnetic Neutron Spin Echo spectroscopy and then focus on the ferromagnetic Spin Echo method, which has not been discussed in the literature so far. Finally, we discuss the implications of the vector nature of the (dipole) interaction between a neutron beam polarization and a magnetic sample for the quantum mechanical description of Larmor precession-based methods.@en

The archetype cubic chiral magnet MnSi is home to some of the most fascinating states in condensed matter, such as skyrmions and a non-Fermi-liquid behavior in conjunction with a topological Hall effect under hydrostatic pressure. Using small angle neutron scattering, we study the evolution of the helimagnetic, conical, and skyrmionic correlations with increasing hydrostatic pressure. We show that the helical propagation vector smoothly reorients from (111) to (100) at intermediate pressures. At higher pressures, above the critical pressure, the long-range helimagnetic order disappears at zero magnetic field. Nevertheless, skyrmion lattices and conical spirals form under magnetic fields, in a part of the phase diagram where a topological Hall effect and a non-Fermi-liquid behavior have been reported. These unexpected results shed light on the puzzling behavior of MnSi at high pressures and the mechanisms that destabilize the helimagnetic long-range order at the critical pressure.

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We have developed and realised a compact high-pressure clamp cell of the piston-cylinder type for Small Angle Neutron Scattering (SANS) and Neutron Spin Echo (NSE) spectroscopy measurements. The cell can pressurise φ5 mm samples up to 1.5 GPa. It is non-magnetic, produces a sufficiently low and flat SANS background with a relatively good neutron transmission and can be used in combination with polarised neutrons. The cell accommodates samples of up to 55 mm³ in volume and adopts a two-layer geometry: a TiZr body (outer layer) and a CuBe2 insert (inner layer). Its design is very compact and can be employed inside cryomagnets featuring a sample bore greater than φ30 mm. We present the cell and illustrate its performances with a series of neutron scattering experiments performed on single-crystalline MnSi.

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