Angle-resolved photoemission study on potential topological insulator ZrTe$_5$

ZrTe$_5$ is a layered-structure material which is predicted to exhibit the quantum spin hall effect in its monolayer limit. Bulk ZrTe$_5$ material is of scientific interest as well, as it might lie within the transition boundary between weak and strong topological insulator. We are using angle-resolved photoemission spectroscopy (ARPES) to investigate the band structure of bulk ZrTe$_5$. Synchrotron data with varied photon energies shows little k$_z$ dependence, which indicates a quasi-two-dimensional band structure; in addition, we observe circular dichroism, which suggests possible spin polarization. We are also working on time-resolved ARPES measurements, hoping to reveal the band structure above the Fermi level, which might give information about the material’s topological properties.