A new look at the ground state properties of Ce2Ir3Al9: Coexistence of two competing energy scales

[摘要] We present an extended research on characterization of the ground state in a polycrystalline compound Ce2Ir3Al9 using powder x-ray diffraction, magnetic susceptibility chi(T), isothermal magnetization M(B), specific heat C-p(T), electrical resistivity rho(T), magnetoresistivity rho(B), thermoelectric power S(T) and thermal conductivity kappa(T) measurements, together with a theoretical description of the obtained data to develop a more profound understanding of the physics in this compound. Ce2Ir3Al9 crystallizes in the orthorhombic Y2Co3Ga9-type of structure (space group Cmcm, No. 63, oC56, Z = 4). The chi(T) and C-p(T)/T data reveal the signatures of intermediate valence behaviour on Ce ions with the approximate value of the Kondo temperature T-K = 96 K and the Sommerfeld coefficient gamma = 31 mJ/mol . K-2. In contrast to the magnetometric and thermodynamic measurements, the transport data (rho(T) and S(T)) indicate the development of the Kondo lattice state. Accordingly, we expect that for Ce2Ir3Al9 the most likely scenario, which develops in a wide T range is the coexistence and competition of two energy scales of interactions between conduction electrons and 4f spins on Ce ions, located in one unique crystallographic site in the unit cell, in consequence carrying out our system from Ce4+(Temp) over bar. Ce3+. At higher temperatures, where the Kondo interaction becomes dominant the influence of the crystal electric field effect seems to play an influential role in the ground state of this compound too. (C) 2021 The Author(s). Published by Elsevier B.V.

[发布日期] 2021-11-25

[关键词] A. rare earth alloys and compounds;C. Kondo effect;Valence fluctuations;Electrical transport;Heat conduction;D. magnetic measurements;Thermal analysis