Point-contact spectroscopy on antiferromagnetic Kondo semiconductors CeT2Al10 (T = Ru and Os)**Project supported by the National Key Research and Development Program of China (Grant Nos. 2017YFA0303101 and 2016FYA0300402), the National Natural Science Foundation of China (Grant Nos. 11674279, 11774404, and 11374257), the Zhejiang Provincial Natural Science Foundation of China (Grant No. LR18A04001), and the Japan Society for the Promotion of

Abstract

We have carried out point-contact spectroscopy (PCS) measurements on one family of antiferromagnetic Kondo semiconductor CeT2Al10 (T = Ru and Os) with a Nèel temperature TN ∼ 27.5 and 28.5 K, respectively. Their PCS conductance curves both exhibit a characteristic coherent double-peak-structure at temperatures below TN, signaling an AFM gap around the Fermi surface. The temperature dependent AFM gap Δ1 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 below TN, which is consistent with opening of a new hybridization gap Δh 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 CeRu2Al10 and CeOs2Al10.