Hybridization gap and Fano resonance in SmB${}_6$

Abstract

We present results of Scanning Tunneling Microscopy and Spectroscopy (STS) measurements on the "Kondo insulator" SmB${}_6$. The vast majority of surface areas investigated was reconstructed but, infrequently, also patches of varying size of non-reconstructed, Sm- or B-terminated surfaces were found. On the smallest patches, clear indications for the hybridization gap and inter-multiplet transitions were observed. On non-reconstructed surface areas large enough for coherent co-tunneling we were able to observe clear-cut Fano resonances. Our locally resolved STS indicated considerable finite conductance on all surfaces independent of their structure.

5 pages, 4 figures