Magnetic properties and magnetic structures of RAgSi (R = Gd-Er) compounds

The magnetic properties of polycrystalline samples of RAgSi compounds have been investigated by neutron diffraction, magnetization and DC susceptibili ty measurements over the temperature range from 1.5 to 300K. All title comp ounds are antiferromagnetic at low temperatures. Neutron diffraction data c ollected above the respective Neel points confirm that they crystallize in the hexagonal ZrNiAl-type structure. The magnetic structure of TbAgSi has n ot been determined due to the complexity of the neutron diffraction pattern s recorded at low temperatures. The antiferromagnetic structures of DyAgSi, HoAgSi and ErAgSi are described, each by the propagation vector k = [k(x), k(x), 0] with k(x) = 0.3311(13), 0.3326(7) and 0.5012(28), respectively. T he Neel temperatures are 13.4K in GdAgSi (from the magnetometric measuremen ts), 21.5K in TbAgSi, 11 K in DyAgSi, 10 K in HoAgSi and 2.6 K in ErAgSi. M agnetization measurements carried out in the temperature range from 4 to 30 K in the presence of external magnetic fields up to 120 kOe show that the m etamagnetic phase transitions are induced in GdAgSi, TbAgSi, DyAgSi and HoA gSi. (C) 2000 Elsevier Science B.V. All rights reserved.