SANS and magnetometry study of the magnetic phase diagram of the B20 helimagnet FeRhSi

This manuscript reports the first direct neutron-scattering evidence for long-period helimagnetism in the newly identified 4d-substituted B20 compound Fe0.5Rh0.5Si. By combining SANS with low-field magnetometry, we establish the magnetic modulation, construct a field-temperature phase diagram, and identify a candidate A-phase region supported by an independent structural signature. The work is important beyond this single compound because it expands the family of chiral B20 helimagnets into Rh-substituted materials, where spin-orbit coupling, disorder, and Dzyaloshinskii-Moriya interactions can be tuned. It will interest researchers in chiral magnetism, topological spin textures, magnetic neutron scattering, and quantum materials, and provides a foundation for future studies of emergent magnetic phases and topology-driven phenomena in chemically tuned chiral magnets.