Chiral Strain Engineering of Polar Semiconductors

Rensselaer Polytechnic Institute, Troy NY

Investigators

Abstract

Nontechnical description Chirality, a concept that describes objects (such as crystals, molecules, or the relationship between electron spin and momentum) that possess a distinct configuration from their mirror image, plays a pivotal role in driving many fundamental phenomena in materials physics. Crystalline chiral solids exhibit a unique spin-momentum relation and robust chiral-induced spin selectivity, making them highly promising for energy-efficient spintronic computing at room temperature. The proposed approach of chiral elastic strain engineering offers a framework that facilitates the exploration and discovery of new chiral materials and phases. This approach not only enables the enriching of basic understanding of chiral electronic properties and their relations with strain, but also has the potential to accelerate the implementation of chiral materials in future spintronics and computing technologies. This award also aims to promote science and engineering education and research training among a diverse range of students, including those from historically underrepresented groups in the field, on the topic of chiral electronic materials. The results gained from this award will contribute to the advancement of future microelectronics, benefiting the overall societal progress of the United States. Technical description Chiral spin-orbit coupling, observed in the surface states of topological insulators, Weyl semimetals, and Rashba/Dresselhaus crystals/systems, plays a crucial role in the design of emerging photonic and spintronic devices for integrated quantum photonics and electronics. Chiral crystals, featuring Kramers-Weyl chiral spin-orbit coupling, can be either metals or insulators, providing a larger energy window for topologically non-trivial behavior compared to topological insulators or Weyl semimetals. Moreover, robust room temperature chiral-induced spin selectivity has been discovered in chiral materials. However, the availability of crystalline chiral semiconductors is limited, which significantly hinders the selection of suitable model systems for studying Kramers-Weyl physics, chiral electronic transport properties, and the development of spintronic devices based on chiral materials. In this project, the principal investigator proposes to utilize elastic strain to transform non-chiral semiconductors into chiral phases that possess topological chiral electronic structures. The goal is to uncover the fundamental relationship between chiral properties and strain fields. The role of electric fields in switching chiral handedness will also be investigated. This project will advance the fundamental understanding of chiral electronic structures, electronic transport, optical and optoelectronic properties, and will expand the materials database concerning chiral spintronic properties and devices for future computing. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.