Transport properties of GdB6 and DyB6

The electrical resistance and absolute thermoelectric power (TEP) have been measured for GdB₆ and DyB₆ in the temperature range 2–30 K. The compounds GdB₆ and DyB₆ order antiferromagnetically atT_N 15.2 and 20.3 K, respectively. Above the Néel temperature the resistivity has a small contribution that is linear inT due to electron-phonon scattering, whereas in the same temperature range the spin-disorder TEP (S_spd) has been evaluated and found to be linear inT. A divergence in the temperature derivative of resistance and TEP has been found atT_N that is consistent with the present theories. There is evidence of a low-temperature phase appearing at 7 K in the resistivity and the TEP data of GdB₆. A minimum in the TEP is found in these compounds below 6 K, which is associated mainly with phonon drag and possibly a magnon contribution. A broad peak in the TEP of DyB₆ around 16 K is thought to be due to crystalline electric field effects.