Experimental and theoretical investigations of strongly correlated FeSb2-xSnx

Thermopower, resistivity, and heat capacity have been measured on eight Sn-substituted FeSb2-xSnx samples with x=0-0.15. A giant peak in the low temperature thermopower of FeSb2 is observed and is similar to what is found in the Kondo insulator FeSi. The ab initio calculated band structure of FeSb2 shows striking similarities to that of FeSi. For the samples with Sn substitution the data indicate that as the Sn content increases FeSb2-xSnx evolves from a Kondo insulator into a heavy fermion metal similar to what is observed for FeSi1-xAlx.