New and exotic phases of condensed matter can be discovered by tuning the interactions in magnetic materials by pressure or chemical substitution. The most notable example in chiral magnetism is provided by the effect of hydrostatic pressure on the properties of the archetype chiral magnet MnSi. In research published in Physical Review B, an international team of researchers carried out a comprehensive small angle neutron scattering (SANS) study of the doping dependence of the helimagnetic correlations in Mn_1−xFe_xSi.

They used SANS measurements, performed on the time-of-flight instrument Larmor, to systematically study the evolution of the helimagnetic correlations as a function of both temperature and magnetic field. Their results show that the long-range helimagnetic order in Mn_1−xFe_xSi is suppressed with increasing iron content and disappears when x is increased to 0.11, above which only finite isotropic helimagnetic correlations persist.  Magnetic fields gradually suppress and partly align these short-ranged helimagnetic correlations along their direction through a complex magnetisation process.  

Related publication: “Evolution of helimagnetic correlations in Mn_1−xFe_xSi with doping: A small-angle neutron scattering study" Phys. Rev. B 98, 184431, DOI: 10.1103/PhysRevB.98.184431

Authors: L. J. Bannenberg (Delft University of Technology), R. M. Dalgliesh (ISIS), T. Wolf (Karlsruhe Institute of Technology), F. Weber (Karlsruhe Institute of Technology), and C. Pappas (Delft University of Technology).

Instruments: Larmor​