Exploring strongly correlated 2D insulators via millikelvin far-infrared spectroscopy

Quantum materials associated with strongly correlated gaps may show unusual electronic, magnetic and optical properties, whose carefully examinations can help reveal the nature of the underlying phases. The energy scale of these gaps is often in the far-infrared (THz) regime and many phenomena are optimized at sub-kelvin temperatures. In this talk, we explore the characterization of strongly correlated gaps and low energy excitations in selected strongly correlated 2D insulators, using our recently developed milli-kelvin FIR spectroscopy instrument. We focus on 2D transition metal chalcogenides, such as thin layers of 1T-TaSe2, where a correlated gap depends strongly on the number of layers.