Large enhancement of the resistive anomaly in the pentatelluride materialsHfTe5andZrTe5with applied magnetic field

The resistivity of single-crystal pentatellurides, ${\mathrm{HfTe}}_5$ and ${\mathrm{ZrTe}}_5,$ has been measured as a function of temperature and applied magnetic field. At zero magnetic field these materials exhibit a peak in their resistivity (at $T_P)$ as a function of temperature that corresponds to an, as yet, undetermined phase transition. The application of a transverse magnetic field (B ⊥ to the current I) has a profound effect on the resistive peak in these materials, shifting the peak to slightly higher temperatures and producing a large enhancement of the resistivity at the peak, up to a factor of 3 in ${\mathrm{ZrTe}}_5$ ${(T}_P=145\mathrm{}\mathrm{K})$ and 10 in ${\mathrm{HfTe}}_5$ ${(T}_P=80\mathrm{}\mathrm{K}).$ Larger magnetoresistance is observed at even lower temperatures, $T<\mathrm{}20\mathrm{}\mathrm{K}.$