Anisotropic electrical resistivity of the Kondo insulator CeRu4Sn6

The intermetallic compound CeRu₄Sn₆ has tentatively been classified as anisotropic Kondo insulator. Here we present electrical resistivity measurements on CeRu₄Sn₆ single crystals, both along the main directions a and c of the tetragonal crystal structure, and v along the diagonal c' of the a-a plane. This direction was selected because c' = differs from c by only 0.2 %, suggesting that the coumpound might alternatively be regarded as quasi-cubic. Amazingly, strong anisotropy is observed not only between a and c but also between c and c'. We analyse the temperature dependent resistivities both with a simple semiconductor model and within a Kondo insulator picture.