Magnetic structure and properties of LaFe13-xGaxC compounds (x=2.9, 6.5)

Neutron diffraction and magnetic measurements for the LaFe13−xGaxC compounds (x=2.9 and 6.5) were carried out in order to investigate their magnetic state. The LaFe10.1Ga2.9C compound is a collinear ferromagnet with magnetic moments of the Fe atoms parallel to the c-axis at T<410K. An average value of the Fe magnetic moments is (2.0±0.1) and (1.9±0.1) μB at 4.2 K according to neutron diffraction and magnetic data, respectively. In the LaFe6.5Ga6.5C compound, coexistence of antiferromagnetic regions and spin-glass behavior at T<86K is observed. The Neel temperature of antiferromagnetic regions and the temperature of spin-glass freezing coincide. A model of the antiferromagnetic arrangement of the Fe-atom magnetic moments has been proposed.