Point-contact spectroscopy on antiferromagnetic Kondo semiconductors CeT₂Al₁₀ (T = Ru and Os)*

We have carried out point-contact spectroscopy (PCS) measurements on one family of antiferromagnetic Kondo semiconductor CeT 2Al10 (T = Ru and Os) with a Nèel temperature T N ∼ 27.5 and 28.5 K, respectively. Their PCS conductance curves both exhibit a characteristic coherent double-peak-structure at temperatures below T N, signaling an AFM gap around the Fermi surface. The temperature dependent AFM gap Δ 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 below T N, which is consistent with opening of a new hybridization gap Δ 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 CeRu2Al10 and CeOs2Al10.