Riemann Surfaces in Layered Van der Waals Nanowires: Precision Twist Moirés, Nanoscale Solenoids, and Screw Dislocation Spin-Orbit Coupling
Abstract
Title: Riemann Surfaces in Layered Van der Waals Nanowires: Precision Twist Moirs, Nanoscale Solenoids, and Screw Dislocation Spin-OrbitVan der Waals (vdW) heterostructures of atomically thin (2D) crystals promise materials integration without the conventional lattice-matching constraints governing 3D-crystalline materials. Of particular interest are twisted heterostructures in which the constituent lattices aremisaligned by a small azimuthal angle. Prior work has shown that interfacial moir patterns in twisted heterostructures support emergent properties such as moir excitons and phonons, as well as strong carrier correlation effects due to ultra-narrow flat bands at small interlayer twist. To date, such twisted structures have been realized exclusively in a planar geometry and fabricatedby mechanical stacking, which is challenging especially at small twist angles.The research proposed here builds on the recent discovery by the PIs that nanowires synthesized by vapor-liquid-solid growth of layered vdW crystals can provide a new architecture for realizing interlayer twists. VdW nanowires show a strong propensity toward incorporating axial screw dislocations, and Eshelby twist due to the dislocation stress field spontaneously produces a chiral structure. Such helical layered nanowires, which resemble a Log z Riemannsurface, represent a scalable platform for realizing vdW interfaces with small twist angles that are controlled by the wire diameter and stabilized by the axial screw dislocation. A primary objective of the proposed work is to explore how such precisely tunable interlayer twists affect optoelectronics, interlayer phonons, and charge transport in vdW nanowires. Besides moirphysics, the helical structure and axial screw dislocations offer additional opportunities for significant scientific adven bypassed by scaling in microelectronics to nanometer dimensions. And screw dislocations in nanowires may be usedto realize novel spin-orbit coupling effects predicted to produce spin textures with long coherence times. Hence, another main objective is to establish the materials science required to realize these systems and to identify the physical principles governing their function.The proposed technical approach combines established methods, such as low-temperature charge transport and micro-Raman spectroscopy, with techniques at the very forefront of the field. In particular, optoelectronic properties will be measured at the moir length scale by combined electron-beam excited luminescence and absorption spectroscopies, locally correlatedwith structural probes on the same vdW nanowires. Other innovative approaches include means for manipulating the twist, synthesis of hollow layered nanotubes, and tuning of the vdW gaps, which will be used in concert to pursue the project goals.A successful completion of the proposed project will provide a fundamental understanding of the effects of interlayer twist moirs on the electronic structure, optoelectronics, phonons, carrier correlations and charge transport for a unique architecture allowing the precise selection of will establish helical nanowires as scalable inductors, solenoids, and spintransport channels. The proposed basic research promises contributions to technologies critical to the Navy and DOD, notably in optoelectronics, photonics, classical and quantum information processing, and via novel device elements, for instance for locally generating high magnetic fields. And the project contributes to the education and training of the military and civilian hightechnology workforce via training and mentoring of the participating students.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 29, 2020
- Source ID
- N000142012305
Entities
People
- Peter Sutter
Organizations
- Office of Naval Research
- United States Navy
- University of Nebraska system