Crystal Structure and Magnetism of Noncentrosymmetric Eu2Pd2Sn.

Mauro Giovannini,Marian Reiffers,Riccardo Freccero,Julian Sereni,Pavlo Solokha,Ivan Čurlík

doi:10.1021/acs.inorgchem.1c00678

Mauro Giovannini, Marian Reiffers + Show 4 more

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https://doi.org/10.1021/acs.inorgchem.1c00678

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Abstract

The new intermetallic compound Eu2Pd2Sn has been investigated. A single crystal was selected from the alloy and was analyzed by single-crystal X-ray diffraction, revealing that this compound possesses the noncentrosymmetric Ca2Pd2Ge structure type being, so far, the only rare-earth-based representative. Bonding analysis, performed on the basis of DOS and (I)COHP, reveals the presence of strong covalent Sn–Pd bonds in addition to linear and equidistant Pd–Pd chains. The incomplete ionization of Eu leads to its participation in weaker covalent interactions. The magnetic effective moment, extracted from the magnetic susceptibility χ(T) is μeff = 7.87 μB, close to the free ion Eu2+ value (μeff = 7.94 μB). The maximum of χ(T) at TN ∼ 13 K indicates an antiferromagnetic behavior below this temperature. A coincident sharp anomaly in the specific heat CP(T) emerges from a broad anomaly centered at around 10 K. From the reduced jump in the heat capacity at TN a scenario of a transition to an incommensurate antiferromagnetic phase below TN followed by a commensurate configuration below 10 K is suggested.

Highlights

Intermetallic compounds based on rare earth elements, such as Ce, Eu, and Yb with different configurations of their felectrons, show a wealth of fascinating properties.[1−3] These systems are potentially interesting mainly due to the anomalous properties of these three rare earths, which are not always in the trivalent (3+) state like the majority of other rare earths
A chemically reasonable structural model was obtained in a few iteration cycles by applying the charge-flipping algorithm implemented in JANA2006.26 In this model the rare earth and Pd atoms are situated in different 16b sites of general symmetry, whereas the remaining Sn atoms occupy the 8a site
The absolute structure for Eu2Pd2Sn was ensured through the refinement of the Flack parameter

Summary

■ INTRODUCTION

Intermetallic compounds based on rare earth elements, such as Ce, Eu, and Yb with different configurations of their felectrons, show a wealth of fascinating properties.[1−3] These systems are potentially interesting mainly due to the anomalous properties of these three rare earths, which are not always in the trivalent (3+) state like the majority of other rare earths. Instead of a negligible magnetic anisotropy, Eu intermetallics frequently exhibit a complex and strongly anisotropic magnetism.[4,5] In some cases, namely for EuNiGe3 and EuPdSn, despite the substantial neutron absorption of Eu, a large-area flat-plate geometry was used to thoroughly investigate the magnetic structure of Eubased intermetallics In both compounds, a complex incommensurate antiferromagnetic scenario with a thermal evolution of the magnetic structure was described in detail.[6,7]. Semiempirical absorption corrections based on a multipolar spherical harmonic expansion of equivalent intensities were employed for all data using the SADABS software.[21] Details about the crystal structure solution and refinement are reported in the Results and Discussion section. Electrical resistivity was carried out using a standard four-probe technique

■ RESULTS AND DISCUSSION

■ CONCLUSIONS

■ ACKNOWLEDGMENTS

■ REFERENCES