Thin Films with Tunable Source Laser-ARPES*

Dirac semimetals (DSMs) have drawn a considerable amount of attention in recent years due to their linear, gapless bands near the Fermi level. The transition metal dichalcogenide ZrTe₂ has been theoretically predicted and experimentally demonstrated to have such a DSM phase, although direct observation of linear dispersion in all three dimensions is yet unreported. Using molecular beam epitaxy, we have grown thin films of ZrTe₂ on insulating sapphire substrates. The DSM phase of ZrTe₂ is investigated by in-vacuo angle-resolved photoemission spectroscopy (ARPES). Using high harmonic generation from a Y-Fi laser, we vary the excitation wavelength of our ARPES experiment to observe the linear dispersion of the reported Dirac cone in all three momentum directions. Further, we examine the change in the DSM phase with the introduction of transition metals dopants. These create ferromagnetic order in ZrTe₂, as confirmed by the square anomalous Hall hysteresis in transport measurements.