Seebeck Effect in Heavy Rare-Earth Single Crystals

Seebeck coefficients $S$ have been measured along the three crystallographic directions $〈11\overline{2}0〉$, $〈10\overline{1}0〉$, and $〈0001〉$ for the heavy rare-earth metals Gd, Tb, Dy, Ho, and Er over the temperature range 7 to 300\ifmmode^\circ\else\textdegree\fi{}K. The $〈10\overline{1}0〉$ and $〈0001〉$ directions of Y were also measured. In the cases of Gd and Tb, a 1000-Oe field along the $〈0001〉$ and $〈10\overline{1}0〉$ directions, respectively, caused no marked change. A significant anisotropy between the $〈0001〉$ direction and the basal plane was found for all the metals except Y. The magnetic order-disorder temperatures are marked by changes in slope in the $S$-versus-$T$ curves. A discontinuity in $S$ at the magnetic transition is evident in the case of Dy.