Magnetization process of itinerant-electron-type helical-spin-glass reentrant magnet Cr_0.81Mn_0.19Ge observed on various spatial scales

The magnetization process of an itinerant-electron-type helical-spin-glass reentrant magnet Cr_1-xMn_xGe was analyzed using magnetic measurement, neutron depolarization analysis and small-angle neutron scattering, each of which has a different spatial resolution. At temperatures ranging from approx. 8 to 13 K, the helical magnetism having a wave vector parallel to the crystal axis is stable in a zero magnetic field. As the magnitude of the field increases, the conical spin structure having a screw axis parallel to the applied field appears, and the cone angle decreases continuously. This change in spin structure primarily determines the macroscopic magnetization process in low magnetic fields. Although a ferromagnetic structure is induced in higher applied fields, magnetization saturation is difficult to achieve due to the inter-domain interaction. At approximately 8 K, spin-glass-like singularity is confirmed by means of the above-mentioned experimental methods. The appearance of spin-glass-like behavior is accompanied by changes in spin configuration on a microscopic scale. This behavior can be interpreted in terms of a mean-field-type picture, based on the spatial scale of the interaction.