Antiferromagnetic order in TbFe sub 2 Al sub 10 and DyFe sub 2 Al sub 10

The magnetic properties of the orthorhombic aluminides TbFe sub 2 Al sub 10 , DyFe sub 2 Al sub 10 and HoFe sub 2 Al sub 10 have been investigated by neutron powder diffraction. Below the Neel temperatures T sub N = 16.5(5) and T sub N = 7.5(5) K the terbium and dysprosium moments show incommensurate magnetic order with the wave vectors k = (0, 0.7977, 0) and k = (0, 0.7836, 0), respectively. TbFe sub 2 Al sub 10 shows a square wave modulated magnetic ordering of the terbium sublattice with a moment direction parallel to the a-axis. In DyFe sub 2 Al sub 10 the dysprosium moments rotate within the ac- plane forming a helical magnetic structure. For HoFe sub 2 Al sub 10 no magnetic order could be observed down to 1.5 K.