Giant resistivity and X-ray diffraction anomalies in low-dimensional ZrTe5 and HfTe5

Abstract Two giant anomalies have been observed in single crystal samples of metallic ZrTe 5 and HfTe 5 : one is an extremely large maximum in the electrical resistivity at low temperature and the other is a correspondingly large maximum in the intensities of certain “forbidden” x-ray reflections, which correlate in temperature with the electrical anomaly.