The magnetic structures and the magnetic phase diagram of the TbMn2(Ge,Si)2 system

Magnetic structures and magnetic phase transitions in natural-layered TbMn2(GexSi1−x)2 compounds have been studied by magnetisation, low-field AC-susceptibility, electrical resistivity and neutron-diffraction experiments. Non-collinear magnetic structures were observed in the concentration range 0 < x < 0.88. In compounds with x<0.4 an additional “intermediate” ferrimagnetic phase was observed (detected by a significant change in the electrical resistivity). The magnetic x−T phase diagram of the TbMn2(GexSi1−x)2 system is constructed and the role of magnetic couplings of different type for the stabilisation of the various magnetic structures is discussed.