Crystal and magnetic structure of TbFe0.25Ge2 compound

The crystal and magnetic structure of polycrystalline TbFe0.25Ge2 sample have been determined. X ray and neutron diffraction studies indicate that this compound has the orthorhombic CeNiSi2 type crystal structure space group Cmcm . The magnetic ordering, based on the neutron diffraction data in low temperature, is described by two components a collinear antiferromagnetic G type and a cosine wave modulated one. In the collinear G type structure the Tb magnetic moment is equal to 3.81 5 mu B and it is parallel to the c axis. The modulated structure is described by the propagation vector k 0.460 8 , 0, 0.305 1 , the Tb magnetic moment equals 7.75 8 mu B , lies in b c and forms an angle 23 2 degrees with the c axis. The collinear component decreases to zero at 22.6 K while the modulated one at 190.8