THz spectroscopic Investigation of Quantum Hall transitions

The project explores quantum Hall transitions (qHt) using THz spectroscopy in state-of-art Bi₂Se₃ topological insulator thin films and in 2D electron gas in ultra-high mobility GaAs heterostructures at milli-Kelvin temperatures. By measuring Faraday rotation spectra in THz spectral range, we study disorder and frequency-dependent scaling of critical exponents of qHt. Additionally, we test recent theories proposing unified framework for integer and fractional qHt. By end of first year, we aim to understand disorder effects and develop a method to quantify disorder in various samples. By end of second year, we seek to provide experimental proof of integer and fractional qHt universality by determining critical exponents. This project will advance our understanding of qHt and its applicability in quantum computing and energy-efficient electronics. Key activities include THz spectroscopy, data analysis, and theoretical modeling, with results submitted to leading peer-reviewed journals.