Large enhancement of the resistive anomaly in the pentatelluride materialsHfTe5 and ZrTe5 with applied magnetic field

The resistivity of single-crystal pentatellurides, HfTe5 and ZrTe5, has bee n 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 perpen dicular to to the current I) has a profound effect on the resistive peak in these materials, shifting the peak to slightly higher temperatures and pro ducing a large enhancement of the resistivity at the peak, up to a factor o f 3 in ZrTe5 (T-p = 145 K) and 10 in HfTe5 (Tp = 80 K). Larger magnetoresis tance is observed at even lower temperatures, T<20 K.