Physical properties of RIr (R = Gd, Tb, Ho) compounds with coexisting polymorphic phases.

The binary compounds GdIr, TbIr and HoIr are synthesized successfully and found to form with macroscopic co-existence of two polymorphic phases: AuBe (C15b) and AuCu-type. The dc magnetization and heat capacity studies confirm that the C15b phase orders ferromagnetically, whereas the AuCu phase remains paramagnetic down to 2 K. The frequency dependent ac-susceptibility data, time dependent magnetic relaxation behavior and magnetic memory effect studies suggest that TbIr and HoIr are cannonical spin-glass systems, but no glassy feature could be found in GdIr.