The effects of low carrier density and carrier compensation on mixed-state thermal transport are investigated beyond the quasiclassical approximation. It is shown that, contrary to the usual observations, the interplay of the two effects leads to an { \it increase} in the thermal conductivity immediately below the upper critical field $H_{ c2}$. Our result can account for the anomalous behavior of the mixed-state thermal conductivity near $H_{ c2}$ recently observed in URu$_2$Si$_2$.
Categories: cond-mat.supr-con cond-mat.str-el