Effects of Fe substitution for isoelectronic Ru on the magnetic and transport properties of CeRu2Al10

Abstract

We have investigated the effects of magnetic Fe ion substitution in Ce(Ru1−xFex)2Al10 on the magnetic and transport properties, when the Kondo insulator CeRu2Al10 with anomalous antiferromagnetic order at TN = 27 K [1] is fully transformed into the archetypal non-ordered Kondo insulator CeFe2Al10 [2]. The characteristic Kondo temperature TK is determined from the magnetic susceptibility, and demonstrates a linear dependence on Fe concentration between 0.6 and 1. With increasing x, the positive maximum in the thermoelectric power just below TN enhances gradually and reaches up to ∼80 µV/K (at T = 40 K) for x = 0.8, which is remarkably as high as ∼4 and ∼1.5 times the corresponding values in CeRu2Al10 and CeFe2Al10 respectively. The magnitude of the lattice thermal conductivity is found to be nearly independent of x, while the electronic thermal conductivity on the other hand decreases by an order of magnitude when x increases from 0 to 0.8. We discuss our results in terms of the extreme electronic sensitive nature between CeRu2Al10 and CeFe2Al10.