Research Projects

The proposed research seeks to deepen our understanding of quantum phenomena in condensed matter systems by investigating novel quantum phases arising at the interface of topological insulators (TIs) and low-density superconductors (LDS). Specifically, the study focuses on the hybridization of the 3D topological insulator BiSbTeSe₂, a material characterized by highly insulating bulk properties and robust, gapless surface states, with indium oxide (InO), a low-density superconducting film exhibiting superconductor-insulator quantum phase transitions and intriguing states like the ‘Bose metal’ and ‘Bose insulator.’ BiSbTeSe₂ demonstrates quantum effects such as the quantum spin Hall effect (QSH) and quantum anomalous Hall effect (QAHE). Coupling it with InO, which features a 2D carrier density comparable to that of TIs, offers a unique platform to explore emergent phenomena. By integrating these two materials, the project aims to uncover the effects of superconducting fluctuations on the TI surface states, potentially inducing superconductivity and modifying the electronic band structure with a newly opened energy gap. Moreover, the interplay of disorder in the LDS film and topological surface states may result in exotic quantum orders and novel manifestations of QSH and QAHE. Through advanced sample preparation techniques, including exfoliation for TIs and controlled growth of LDS films under varying conditions (temperature, oxygen pressure), the project will explore the TIs/LDS bilayer system. Electronic and magneto-transport experiments, along with noise measurements at low temperatures, will be employed to probe these interfaces. The ability to tune carrier density in TIs via gate voltage will allow precise control over accessing the Dirac point and modulating superconductivity in the bilayer. Notably, the system’s disorder and low carrier density may enable the realization of new topological orders and unconventional superconducting symmetries, as observed in analogous systems like graphene and high-Tc superconductor bilayers. This research is aligned with national initiatives like the ‘India Semiconductor Mission,’ ‘Make in India,’ and ‘Atmanirbhar Bharat,’ contributing to foundational knowledge in semiconductor devices, materials characterization, and manufacturing. The project also promises to offer students hands-on experience in cutting-edge experimental techniques, equipping them with skills directly relevant to the semiconductor industry. By exploring the physics of these hybrid systems, the research has the potential to advance quantum device technologies and uncover groundbreaking insights into low-dimensional quantum materials.