Regensburg 2019 – scientific program
TT 54.11: Talk
Thursday, April 4, 2019, 12:15–12:30, H22
Near-field optical probes of the current- and temperature-driven insulator-to-metal transition in the Mott insulator Ca2RuO4 — •Desislava Daskalova1,2, Parmida Shabestari1,2, Hao Chu1,2, Maximilian Krautloher1, Joel Bertinshaw1, Bernhard Keimer1, and Stefan Kaiser1,2 — 1Max Planck Institute for Solid State Research, Stuttgart, Germany — 24th Physics Institute, Stuttgart University, Germany
Many-body effects in correlated materials give rise to exciting quantum phenomena and phases of matter. Here we study calcium ruthenate (Ca2RuO4), a Mott insulator at room temperature, because it exhibits interesting magnetic, transport and structural properties. The delicate balance in its ground state is easily perturbed by temperature, pressure and small electric field (40 V/cm) which all induce an insulator-to-metal transition (IMT). However, distinctly different metallic phases in a temperature- or current-driven case are being stabilized. One goal is to distinguish the different mechanisms driving the transition, especially to understand the current-driven IMT which remains to be fully explained.
To this end we probe the changes in the optical properties of Ca2RuO4 during the current- and temperature-driven IMT using far-field infrared spectroscopy and scattering-type scanning near-field optical microscopy. Probing the nanoscale optical response throughout the transition allows us to identify the Mott insulating and metallic phases. We image the two different phases of Ca2RuO4 coexisting and evolving in a manner, characteristic to the driving mechanism.