Magnetic, Transport, and Phonon Properties of the Trivalent Eu Metallic Compound EuBe₁₃

Abstract

Magnetic susceptibility χ, specific heat C, and electrical resistivity ρ measurements have been performed on singlecrystal EuBe 13 in the temperature range between 2 and 300 K to investigate its phonon property and the valence state of the Eu ion. The obtained χ(T ) curves obey a typical Van Vleck susceptibility for Eu 3+ with a nonmagnetic ground state in the entire measured temperature range. In the case of C(T ), we observed the coexistence of Debye and Einstein phonon modes with characteristic Debye and Einstein temperatures of θ D ∼ 835 K and θ E ∼ 167 K, respectively, which are in good agreement with those previously reported for other isostructural MBe 13 compounds (M = rare earths and actinides). The ρ(T ) curve for EuBe 13 shows an unusual T 3 -like dependence at low temperatures, as also observed for the nonmagnetic isostructural compound LaBe 13 , which can be reproduced well by calculations based on electron-phonon scattering using the estimated θ D and θ E . We also summarized the relationship between the Eu-valence state and the free distance between the Eu ion and the first-nearest-neighbor atoms in several Eu-based cubic compounds, and argued that EuBe 13 takes the Eu 3+ state despite its larger free distance than other Eu 3+ compounds.

Rare-Earth Atomic Motion in RBe13 (R: La, Pr, Sm)

“…This crystal structure has two Be cages: one called 8a site includes a rare-earth R atom in 24 Be atoms; the other called 8b site includes a Be atom in 12 Be atoms. Macroscopic measurements such as specific heat measurements and X-ray diffraction experiments [7][8][9] suggests low-lying optical modes related to rare-earth atomic motion, which correspond to Einstein temperature of about 170 K, corresponding to 14.7 meV. Although inelastic neutron scattering of UBe 13 using polycrystalline sample was reported [10][11][12], no phonon dispersion relations were reported with our best knowledge.…”