Thermal conductivity, thermoelectric power and Mössbauer investigations on atiferromagnetic CeFe1.7Ir0.3Al10

CeFe 2 Al 10 is known to exhibit a Kondo semiconducting behavior without any signature of long range magnetic ordering. A partial Ir substitution for Fe in CeFe 2 Al 10 is found to drive the system towards long range magnetic ordering, and a 15% Ir substitution is found to result in an antiferromagnetically ordered state below 3.1(2) K in CeFe _1.7Ir _0.3Al ₁₀. We present the results of the electrical resistivity ρ , thermal conductivity κ and thermoelectric power S measurements as a function of temperature T , and ⁵⁷Fe Mössbauer spectroscopy on polycrystalline CeFe _1.7Ir _0.3Al ₁₀. The ρ ( T ) exhibits Kondo lattice behavior and presents evidence for the formation of a superzone gap in antiferromagnetic state. We estimate Kondo temperature T K ≈ 18 K. The κ ( T ) does not show any anomaly and reflects a phonon dominated thermal transport. The Lorenz number L ( T ) = κ ( T ) ρ ( T ) / T is found to be much larger than the theoretical Sommerfeld value L 0 which also reflects a phonon dominance. The S ( T ) exhibits a minimum at low T ( S min ≈ − 2 . 3 μ V/K, T S min ≈ 30 K) and a maximum at high T ( S max ≈ 5 . 4 μ V/K, T S max ≈ 225 K). The S ( T ) data are described by a two-band model with contributions from two Lorentzian shaped f -bands. From the analysis of S ( T ) , we infer that while one of the contributing f -band lies 22 K below the Fermi energy E F , the other one is at 190 K above E F . The ⁵⁷Fe Mössbauer spectra collected in zero field do not show clear evidence of magnetic ordering, however, the Mössbauer measurements in external fields support an antiferromagnetic ordering in CeFe _1.7Ir _0.3Al ₁₀.