Electronic evidence of temperature-induced Lifshitz transition and topological nature in ZrTe5

The topological materials have attracted much attention for their unique electronic structure and peculiar physical properties. ZrTe₅ has host a long-standing puzzle on its anomalous transport properties manifested by its unusual resistivity peak and the reversal of the charge carrier type. It is also predicted that single-layer ZrTe₅ is a two-dimensional topological insulator and there is possibly a topological phase transition in bulk ZrTe₅. Here we report high-resolution laser-based angle-resolved photoemission measurements on the electronic structure and its detailed temperature evolution of ZrTe₅. Our results provide direct electronic evidence on the temperature-induced Lifshitz transition, which gives a natural understanding on underlying origin of the resistivity anomaly in ZrTe₅. In addition, we observe one-dimensional-like electronic features from the edges of the cracked ZrTe₅ samples. Our observations indicate that ZrTe₅ is a weak topological insulator and it exhibits a tendency to become a strong topological insulator when the layer distance is reduced.