Engineering the Properties of Orbitronic Nanomaterials
Abstract
We will develop new routes to topological materials that exploits orbital rather than spin degrees of freedom in a band structure. These studies will focus on materials containing lighter elements such as silicon where the spin-orbit coupling energy scale is negligibly small in order to enable us to manipulate the electronic properties via potentials that manipulate orbital degrees of freedom. The rationale is that the fundamental mechanism for novel quantum geometric effects in the dynamics is the k-space connection which describes the change of the internal polarization of a quantum state under differential displacement in momentum space. Coupling to the orbital degree of freedom can produce a topologically nontrivial texture, compactly represented by the k-space Berry curvature. This approach has not received the attention that it deserves and the development of topological band physics in lighter materials will immediately bring into play a wide palette of existing conventional electronic materials such as silicon. Topological orbitronics can have a transformative impact by combining new functionalities with already existing technologies for fabricating conventional electronic devices, properties of which will be robust at room temperature due to the different energy scales associated with these phenomena. We will utilize the unique interplay of geometry, shape and confinement in nanomaterials along with symmetry breaking fields to produce such nontrivial and unprecedented electronic functionalities that are not present otherwise. Our effort will be mostly directed at conventional electronic materials, where our vision is that novel electronic and optoelectronic phenomena are accessible by controllably fabricating them into desired shapes and geometries. This approach will also exploit the strongly confined electrical and optical excitations supported in these systems which are sensitive to boundary effects and thereby enable precisely tunable responses and new device applications. The fundamental tasks that will be addressed in this project and for which our team is uniquely positioned. Discovery of new orbitronic materials with Berry curvatures arising from orbital degrees of freedom. Fabrication and manipulation of orbitronic nanomaterials using confinement, shape and morphology. It is envisioned that these initial studies will pave the way for far more complex electronic phenomena controlled by orbital degree of freedom, which are much more shape dependent than highly local spin orbit scattering length scales. Therefore, these properties can be manipulated by scalar potentials, edges and other geometrical parameters. Our proposed program will open up completely new applications of conventional materials containing only light elements (e.g, Si) to enable their continued use in future devices and also discover new materials and systems with properties that have not been envisioned. Design and understanding of these new systems will have applications in computing, photonics, medical diagnostics and sensing and will pave the way for unconventional devices, enabled by active materials and new coupling mechanisms for robust functionalities where more information can be encoded, stored, transported or manipulated, all relevant to the broad vision of the army s mission.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 16, 2018
- Source ID
- W911NF1710436
Entities
People
- Ritesh Agarwal
Organizations
- Army Contracting Command
- United States Army
- University of Pennsylvania