Investigation of the magnetic ground state of PrRu$_2$Ga$_8$ compound

Abstract

We have investigated the ground state properties of the orthorhombic structure compound PrRu2Ga8 through electronic and magnetic properties studies. The compound crystallizes in the CaCo2Al8-type structure, belonging to space group P bam (No. 55). The temperature dependence specific heat shows a λ-type anomaly at TN = 3.3 K, indicating a bulk phase transition probably of antiferromagnetic origin. At the Néel temperature TN , the entropy approaches the value of 4.66 J/mol.K which is about 0.8Rln(2), where R is the universal gas constant. The analysis of the low temperature specific heat gives γ = 46 mJ/mol.K 2 . The temperature dependence DC magnetic susceptibility χ(T ) confirms the anomaly at 3.3 K and follows the Curie-Weiss law for temperatures above 50 K, with the calculated effective magnetic moment, µ eff = 3.47(2) µB/Pr and Weiss temperature θp = -7.80(1) K. This effective magnetic moment value is in good agreement with the Hund s rule theoretical free-ion value of 3.58 µB for Pr 3+ . The electrical resistivity data also shows an anomaly at TN and a broad curvature at intermediate temperatures probably due to crystalline electric field (CEF) effects. The Pr 3+ in this structure type has a site symmetry of Cs which predicts a CEF splitting of the J = 4 multiplet into 9 singlets and thus rule out in principle the occurrence of spontaneous magnetic order. In this article we discuss the magnetic order in PrRu2Ga8 in line with an induced type of magnetism resulting from the admixture of the lowest CEF level with the first excited state.

Strong magnetic anisotropy in PrRu2Ga8 and PrCo2Al8 single crystals

“…The γ value obtained from the fitting is 31.06 and 11.59 mJ mol −1 K 2 for PrRu 2 Ga 8 and PrCo 2 Al 8 , respectively. The γ value of PrRu 2 Ga 8 is larger than ordinary metals (∼10 mJ mol −1 K 2 ) [29], suggesting an enhanced quasi-particle mass.…”

“…PrFe 2 Ga 8 displays an antiferromagnetic (AFM) order around 14 K and anisotropic magnetic properties [28]. Compared with PrFe 2 Ga 8 , PrRu 2 Ga 8 and PrCo 2 Al 8 have been reported to AFM order at much lower temperatures [27][28][29]. However, magnetic anisotropies for PrRu 2 Ga 8 and PrCo 2 Al 8 have not been studied.…”