Point-contact spectroscopy on antiferromagnetic Kondo semiconductors CeT 2Al10 (T = Ru and Os)

We have carried out point-contact spectroscopy (PCS) measurements on one family of antiferromagnetic Kondo semiconductor CeT2Al10(T= Ru and Os) with a Neel temperatureT(N)similar to 27.5 and 28.5 K, respectively. Their PCS conductance curves both exhibit a characteristic coherent double-peak-structure at temperatures belowT(N), signaling an AFM gap around the Fermi surface. The temperature dependent AFM gap Delta(1)follows a Bardeen-Cooper-Schrieffer (BCS)-like mean-field behavior with a moderate gap anisotropy for PCS along different crystal axes. Another asymmetric gap-like feature is observed for both compounds at temperatures far belowT(N), which is consistent with opening of a new hybridization gap Delta(h)inside the long-range ordered AFM state. Our results suggest a common itinerant nature of the anomalous AFM ordering, constraining theoretical models to explain the AFM origin in CeRu(2)Al(10)and CeOs2Al10.