Thermal conductivity, thermoelectric power and Mossbauer investigations on antiferromagnetic CeFe1.7Ir0.3Al10

CeFe2Al10 is known to exhibit a Kondo semiconducting behavior without any signature of long range magnetic ordering. A partial Ir substitution for Fe in CeFe2Al10 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 CeFe1.7Ir0.3Al10. We present the results of the electrical resistivity rho, thermal conductivity kappa and thermoelectric power S measurements as a function of temperature T, and Fe 57 Mossbauer spectroscopy on polycrystalline CeFe1.7Ir0.3Al10. The rho T exhibits Kondo lattice behavior and presents evidence for the formation of a superzone gap in antiferromagnetic state. We estimate Kondo temperature T K approximate to 18 K. The kappa T does not show any anomaly and reflects a phonon dominated thermal transport. The Lorenz number L T kappa T rho 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 approximate to 2.3 mu V K, T Smin approximate to 30 K and a maximum at high T S max 5.4 mu V K, T smax approximate to 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 Fe 57 Mossbauer spectra collected in zero field do not show clear evidence of magnetic ordering, however, the Mossbauer measurements in external fields support an antiferromagnetic ordering in CeFe1.7Ir0.3Al1