Magnetic phase transitions in RMnGe (R=Tb, Dy) compounds induced by high magnetic fields

Magnetization isotherms for polycrystalline TbMnGe and DyMnGe compounds were measured at the temperature 4.2 K in pulsed magnetic fields (up to 360 kOe). The received isotherms demonstrate the appearance of metamagnetic transitions at low temperatures. Both compounds crystallize in the orthorhombic TiNiSi-type structure. It was found that the magnetic phase transitions with a destruction of ferrimagnetic spiral structure occur in the TbMnGe and DyMnGe compounds in high magnetic fields. An attempt was undertaken to explain the nature of these transitions using the results of the powder neutron diffraction and the qualitative estimation of the exchange interaction values on the basis of the molecular field theory.