Physical properties of RIr₃ (R = Gd, Tb, Ho) compounds with coexisting polymorphic phases

Abstract

The binary compounds GdIr3, TbIr3 and HoIr3 are synthesized successfully and found to form in macroscopic co-existence of two polymorphic phases: C15b and AuCu3-type. The dc magnetization and heat capacity studies confirm that C15b phase orders ferromagnetically, whereas the AuCu3 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 TbIr3 and HoIr3 are cannonical spin-glass system, but no glassy feature could be found in GdIr3. The critical behavior of all the three compounds has been investigated from the magnetization and heat capacity measurements around the transition temperature (T C). The critical exponents α, β, γ and δ have been estimated using different techniques such as Arrott-Noaks plot, Kouvel-Fisher plot, critical isotherm as well as analysis of specific heat data and study of magnetocaloric effect. The critical analysis study identifies the type of universal magnetic class in which the three compounds belong.arXiv:1904.04807v1 [cond-mat.mtrl-sci]

Similar and Dissimilar Properties of Polymorphic Phases of NdIr3

“…Taking cues from the earlier reported results in some other members of RIr 3 (R = Gd, Tb, Dy, Ho, Er) series of compounds, 35−37 we have restricted p AuCu 3 to 0 K. The fitting yields p AuBe 5 = 7 K, which is very close to the T C of the material. Moreover, as GdIr 3 forms in the AuBe 5 -type structure, it exhibits ferromagnetic ordering at ∼83 K, 35 deGennes scaling suggests that the NdIr 3 , forming in the same structure, should exhibit Curie temperature ∼ 9.62 K (=0.116 × 83 K), which is close to our experimentally reported value (10 K). Matching of theoretically estimated Weiss temperature with the experimentally observed Curie temperature confirms that the AuBe 5 -type phase only contributes to the magnetic order.…”

“…It was also pointed out in the literature that the stability of NdIr 3 , GdIr 3 , and DyIr 3 compounds lie at the borderline of the said two (AuCu 3 - and PuNi 3 -type) crystal structures. It should also be noted that a few RIr 3 (R = Gd, Tb, Dy, Ho, and Er) compounds − have also been reported to form as a rare coexistence of two polymorphic structures of AuCu 3 -type and a newer structure of AuBe 5 -type (reported earlier for RRh 3 and RPt 3 compounds) that was never predicted for any RIr 3 compounds (Figure ). It was also reported that while AuBe 5 -type RIr 3 (R = Gd, Tb, Dy, Ho, and Er) compounds mentioned above exhibit ferromagnetic ordering at low temperatures, their AuCu 3 -type polymorphic counterparts remain paramagnetic down to 2.5 K. − Another recent report on PuNi 3 -type NdIr 3 , formed after annealing at 1350 °C for 36 h and again at 1370 °C for 36 h under high vacuum, suggested the ferromagnetic ground state for that phase as well .…”

“…The lowering of saturation moment could be due to the CEF effect of Nd 3+ ions. It could also be possible that a fraction of NdIr 3 belonging to the AuBe 5 -type phase exhibits the spinglass behavior, as reported earlier in some other members of the RIr 3 series, 35 which would also reduce the saturation magnetization. The observation of ferromagnetic ordering at 10 K in the AuBe 5 -type phase of NdIr 3 is a highly unusual and fascinating observation as the other polymorphic phase belonging to the PuNi 3 -type was also reported to show a similar Weiss temperature (=5.4 K) and Curie temperature (=10.6 K).…”

Investigation of structural and magnetoelectronic properties of new half‐metallic Heusler alloys Ru2VGexSb1−x (x = 0, 0.5 and 1): A density functional theory study

“…[ 13 ] Moreover, S. Mondal and coworkers have performed an experimental work using X‐ray diffraction (XRD) and resistivity measurements of Ru 2 VAl and Ru 2 VGa. [ 14 ] On the other hand, they have reported in a similar work the structural and thermal properties, as well as the electrical resistivity, of the same compounds. [ 15 ] More recently, I. H. Bhat and D. C. Gupta computed the magnetic and electronic characterization of Ru 2 VGe, and Ru 2 VSb Heusler alloys have been studied using the ab initio method within the GGA scheme.…”

“…[ 14 ] On the other hand, they have reported in a similar work the structural and thermal properties, as well as the electrical resistivity, of the same compounds. [ 15 ] More recently, I. H. Bhat and D. C. Gupta computed the magnetic and electronic characterization of Ru 2 VGe, and Ru 2 VSb Heusler alloys have been studied using the ab initio method within the GGA scheme. [ 16 ] After our careful search of the literature, there is no experimental work or theoretical research available concerning Ru 2 VGe 0.5 Sb 0.5 Heusler quaternary alloy, which represents the fusion between the Ru 2 VGe and Ru 2 VSb ternary compounds.…”