Magnetic properties of ZrNiAl-type R3Mn3GeGa2 compounds (RÂ =Â Y, Gd, Tb, Dy, Ho and Er)

In zero applied field, Ho3Mn3GeGa2 has the magnetic ordering temperature at TN = 175(5) K and Tm = 45(5) K, whereas Er3Mn3GeGa2 show magnetic transitions at TN = 170(5) K and Tm = 35(5) K. Neutron diffraction study reveals that the wave vector K1 is [1/3, 1/3, 0] for both the compounds. However, in Ho3Mn3GeGa2, the components with wave vector K2 = [1/2, 1/2, 0] appear on both rare earth and manganese sublattices below 45(5) K. Both the manganese and rare earth magnetic moments order in a noncollinear sine modulated magnetic structure in these compounds.