Research

Designing noiseless and dissipationless spintronics devices have been a major research area for the scientific community for more than two decades. This has motivated extensive research on quantum materials and exotic quantum states, including magnetic and non-magnetic 2D/3D topological materials. Our group is working on the complex dependence of quantum states on fundamental chemical and structural parameters and how to modify these parameters through strain, doping, or changes in geometry to maximize material performance. Our research projects are: (1) Using DFT and tight-binding models, we will study the electronic, magnetic, and optical properties, as well quantum Anomalous Hall Effect of the predicted intrinsic magnetic topological insulators in families such as MnA_2nX_3n+1 (A = Bi, Sb; X = Te, Se); (2) the complex dependence of topological phases on fundamental electronic and structural parameters, as well as information on how to modify these parameters through an external magnetic field, strain, doping, or change in geometry, to maximize material performance.

Atomic thin two-dimensional materials with intrinsic magnetic moments (2D Magnets) have recently emerged as the newest class of two-dimensional materials (2D Materials), following the discovery of a single atomic layer of chromium tri-iodide (CrI₃) and chromium germanium telluride (Cr₂Ge₂Te₆) crystals. Since then, there has been a surge of 2D magnets, making 2D magnetism one of the most interesting contemporary topics in condensed matter physics and device engineering. Contrary to the long-standing belief on the instability of 2D magnetic ordering, following the Mermin-Wagner theorem, growing experimental demonstrations have provided practical evidence of 2D magnets. As such, these candidates, including their 2D van der Waals (2D-vdW) heterostructures with a number of other 2D materials, have great promises for atomic-scale spintronics and hybrid semiconductor devices. Magnetic Skyrmions, a class of topological spin textures in certain semiconductor materials, including thin films, have been actively studied as an alternate but fundamentally different information carrier promising a new field of skyrmionics. In this project, we study the evolution of atomic structure associated with the lattice distortion and its effects on the local spin texture, phonon modes, and magnon mode.

Quantum computers (QCs) can simulate weakly and strongly correlated systems exponentially faster than classical computers. Due to materials limitations for supporting interconnected qubits, current quantum computers can perform ab-intio calculations only for few atoms. New materials, as well as quantum chemical methods, are needed for addressing this urgent challenge. Recently, Galli and co-workers (Ref) have developed the quantum embedding theory (QET) to study defects in solids using current quantum computers and show that QET is scalable to large systems and that it can include effects of exchange-correlation interactions of the environment on the active regions to allow going beyond the commonly available approximations. Here, we are using the same procedure developed by Prof. Gali and co-workers.

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have attracted significant interest in the last decade because of their novel exotic properties. Specifically, charge density wave (CDW) phase transitions in layered metallic TMDs materials are exciting from a fundamental point of view because their unique structural states are due to correlated electrons interaction and strongly depend on the type of atoms, the thickness of the sample, etc. A complete understanding of CDW phases in various materials is necessary for the successful applications of CDW materials in nano-devices. The long-term goal of this proposal is to investigate the effect of defects (doping and vacancy) and thickness on CDW phase transitions, electronic structures, and transport properties in CDW materials (Example: 2H-TaSe₂) by using density functional theory (DFT) and various experimental technics. This project proposal is divided into two parts. (1) Study the effect of defects on the complex structural evolution occurring during CDW phase transitions for CDW materials. (2) Study the vibration properties of the equilibrium CDW configuration in the presence of defects and compare them to the defect-free case to correlate the found results with the fundamental properties of the CDW phenomenon.