Valleytronics in Two-Dimensional Quantum Materials
Symmetry-breaking light–matter interactions in low-dimensional quantum materials
Overview
We investigate valley-selective optical excitation and polarization-controlled electronic responses in two-dimensional quantum materials and heterostructures. Circularly polarized light enables selective population of inequivalent valleys, providing a powerful handle to control valley polarization and coherence. By combining polarization-resolved optical spectroscopy with electrical transport measurements, we probe valley-dependent carrier dynamics and photocurrent generation. Our work clarifies the mechanisms governing valley selectivity, relaxation, and coupling to external stimuli. These studies contribute to the development of valleytronic and opto-spintronic devices based on low-dimensional materials.
Scientific Motivation In two-dimensional semiconductors, the valley degree of freedom offers a new information carrier beyond charge and spin. Optical selection rules allow direct access to individual valleys using circular polarization, enabling non-invasive control of electronic states. Understanding valley-dependent optical and transport phenomena is essential for realizing next-generation information and optoelectronic technologies.
Key Research Topics
Valley-selective excitation using circular polarization
Valley polarization and coherence in 2D materials
Polarization-dependent photocurrent generation
Valley dynamics in heterostructures and alloys
Valleytronic and opto-spintronic device concepts
Experimental Approaches
Polarization-resolved photoluminescence and absorption spectroscopy
Helicity-dependent photocurrent measurements
Electrical transport under optical excitation
Confocal microscopy and Raman spectroscopy
k-space and angle-resolved optical characterization
Device fabrication and characterization of 2D heterostructures
Representative Results
Demonstration of valley-selective optical responses
Observation of polarization-dependent photocurrents
Identification of mechanisms governing valley relaxation and control
Device-level implementation of valleytronic functionalities
