Surface Electronic States Induced High Terahertz Conductivity of CoO Microhollow Structure.

Herein, we report the observation of unusual electronic and magnetic phases in traditional antiferromagnetic CoO micromaterials and modulation of their properties on a temperature scale. In particular, we demonstrate a comparative low-energy carrier dynamics of CoO microflower and microhollow flower (MHF) structures of same average size of 2 μm to unravel the ground-state information induced by surface electronics across the insulator-semiconductor transition using terahertz (THz) time domain spectroscopy. Interestingly, the THz optical constants of these structures are found to exhibit remarkably distinct features both as a function of frequency and temperature.