Energy gap in the Kondo semiconductor CeRhAs

Electron tunneling measurements have been carried out on the orthorhombic Kondo semiconductor CeRhAs using break junction. The measurements reveal the gap size 2Delta (4 K)= 0.5 +/- 0.1 eV. This compound exhibits the susceptibility maximum at T-Z = 510 K, below which the gap is believed to open. The gap ratio 2Delta/k(B)T(Z) = 12 +/- 3 is consistent with that for the isostructural CeNiSn and CeRhSb, thereby indicating the same mechanism of the gap creation among the compounds. (C) 2002 Elsevier Science B.V. All rights reserved.