Thermoelectric Property of SmT 2 Al 20 (T = Ti, V, and Cr) at Low Temperatures

Thermoelectric properties for cubic SmT2Al20 (T = Ti, V and Cr) compounds with the 8 quartet ground state are presented. These compounds manifest a Kondo-type anomaly below room temperature in the electrical resistivity, and undergo a field-insensitive antiferromagnetic ordering at the Neel temperature TN = 6.5 K (T = Ti), 2.9 K (T = V) and 1.8 K (T = Cr). Furthermore, the emergence of the heavy electron state below TN is suggested by the observation of a large Sommerfeld coefficient  for the each compound. Our present study revealed that the thermoelectric power S shows a positive peak related to the Kondo effect at temperatures roughly above 100 K for T = Ti and V. S for T = Cr is similar to that of its La counterpart in the same temperature range, showing no clear Kondo anomaly. On the other hand, a negative peak in S is observed slightly above the respective TN. At lower temperatures, a positive peak appears for all the compounds. In addition, for T = V, a large S/T of 5 V/K 2 is attained in the zero-temperature limit, which is almost the same as that expected from the large  ~ 720 mJ/(mol K 2 ).