Magnetic Structure of Mn0.7Fe0.3Ge Compound under Quasi-Hydrostatic Pressure

In the paper, the helical magnetic structure of the Mn0.7Fe0.3Ge compound under a high quasihydrostatic pressure of up to 1 GPa was investigated for the first time by small-angle neutron scattering (SANS) in a wide range of temperatures (5–300 K) and magnetic fields (0–5 T). It is shown that the wave vector of the magnetic spiral increases with pressure. The field-temperature (H–T) phase diagrams were plotted for the compound at different pressures up to P = 1 GPa. It was shown that the applied pressure leads to an increase of all the values of critical magnetic fields corresponding to the beginning of the process of the transition of the polycrystalline sample to the conical phase (Hc1), the end of the process (Hc1m) and the transition to the ferromagnetic phase (Hc2), at low temperatures, which may indicate the stabilization of the magnetic system under the external pressure. It was found that the region of existence of a skyrmion lattice (or a phase) decreases with the pressure increase both in the temperature and field ranges. This suggests that the influence of Dzyaloshinskii–Moriya exchange interaction is suppressed when the cell constant is decreased.