Tunneling Spectroscopy Studies of SmB6 and YbB12

M. Baťková a, I. Baťko a, E. Konovalova b and N. Shitsevalova b a Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 040 01 Košice, Slovak Republic b Institute for Problems of Material Science, NASU, Krzyzhanovskii str. 3, 252680 Kiev, Ukraine

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Received: 9 07 2007;

Reported electron tunneling studies of SmB6 and YbB12 in the temperature region with a strongly temperature activated transport reveal a qualitative change of tunneling regime upon cooling. While the differential conductance curves above 50 K resemble the tunneling between two different metals, the spectra observed at 4.2 K are typical of the tunneling between a metal and a (narrow-gap) valence fluctuating semiconductor.

DOI: 10.12693/APhysPolA.113.255 PACS numbers: 71.28.+d, 75.30.Mb, 73.40.Gk