Thermoelectric Property of SmT₂Al₂₀ (T = Ti, V, and Cr) at Low Temperatures

Abstract

Thermoelectric properties for cubic SmT 2 Al 20 (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 T N = 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 T N 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 T N. 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).

Magnetic and Thermal Properties of SmRh$_2$Zn$_{20}$ Single Crystal

“…It is contradictory, however, to the fact that the ground state of Sm ions in all SmT r 2 Al 20 is said to be a quartet Γ 8 of trivalent Sm. Kuwai et al measured 12) the thermoelectric power S of SmT r 2 Al 20 (T r = Ti, V, Cr) and found the large values of ∆S /T at temperatures above and near the Néel temperature T N . The large values of S correspond approximately to the large values of C/T since S is proportional to C when both originate from the density of states of the conduction electrons at the Fermi energy.…”