Magnetic structures and magnetic phase transitions in RAuIn (R = Tb, Ho) compounds

TbAuIn and HoAuIn compounds crystallize in the hexagonal ZrNiAl-type struct ure and order magnetically below 35 K for R = Tb and 4.8 K for R = Ho. In t he case of TbAuIn a noncollinear antiferromagnetic structure described by t he propagation vector k = (0, 0, 1/2) is stable in the temperature range fr om 1.5 K up to T-N. The magnetic structure of HoAuIn determined at 1.5 K is noncollinear antiferromagnetic one. This low temperature magnetic structur e could be described by two propagation vectors k(1) = (0, 1/2, 1/2) and k( 2) = (0, 0, 1/2) - At T = 2.5 K an additional phase transition to a modulat ed structure is observed.