CAREER: Quantum spin liquids meet spintronics: Theory of probing quantum spin liquids with spin Hall effects

NONTEHCNICAL SUMMARY This award supports theoretical research at the intersection of quantum magnetism and spin-electronics (also known as spintronics) with a general aim to find spin-sensitive probes of a class of materials known as quantum spin liquids, in which the atomic spins perpetually fluctuate rather than order in a fixed configuration. This strongly disordered spin configuration of quantum spin liquids endows them with a range of unusual and potentially beneficial properties including the possibility of offering a platform that may realize quantum computation. One of the challenges in the field is that experimental results on candidate quantum spin liquid materials often show conflicting results or lend themselves to multiple theoretical interpretations. It is, therefore, important to develop novel methods that examine and characterize candidate quantum spin liquid materials. With the support of this CAREER award, the research team will address this issue by integrating concepts and experimental techniques from spintronics with those of quantum magnetism and propose novel probes of these materials. By contributing to the discovery and characterization of quantum spin liquids, outcomes of this project may, in the long run, enable new technologies in quantum communication and computation, and help create opportunities in numerous aspects of modern life, including drug design, weather forecasting, and logistics optimization. This award also supports educational and outreach activities that are aimed at contributing to the growth of the US STEM workforce and broadening participation within it. The PI will (i) mentor doctoral and undergraduate students in their research, (ii) deliver annual webinars on spintronics at the New York Academy of Sciences Afterschool STEM Mentoring Program and provide research mentoring for New York City middle and high school students from underrepresented demographic groups, and (iii) develop a computational spintronics course for Queens College undergraduates and create a doctoral course on nonequilibrium quantum many-body systems for the City University of New York graduate students. TEHCNICAL SUMMARY This award supports theoretical research at the intersection of quantum magnetism and spintronics with an aim to offer new pathways to realize spin-sensitive probes of quantum spin liquids. The PI and his team will theoretically analyze spintronics-inspired devices to (i) develop a dynamical probe of quantum spin liquids based on spin Hall effects, (ii) quantify spin transport through the Kitaev quantum spin liquid using spin Hall-based spin injection and detection, and (iii) analyze the nonequilibrium behavior of an open Kitaev quantum spin liquid in the presence of spin Hall-based spin current injection. The concepts underlying the proposed probes are universal: such probes can be applied to all quantum spin liquids. Activities supported by this CAREER award will thus fuel the birth of a new line of research that investigates how spin-sensitive probes based on spintronics phenomena can facilitate the experimental identification and characterization of quantum spin liquids. This award also supports educational and outreach activities that are aimed at contributing to the growth of the US STEM workforce and broadening participation within it. The PI will (i) mentor doctoral and undergraduate students in their research, (ii) deliver annual webinars on spintronics at the New York Academy of Sciences Afterschool STEM Mentoring Program and provide research mentoring for New York City middle and high school students from underrepresented demographic groups, and (iii) develop a computational spintronics course for Queens College undergraduates and create a doctoral course on nonequilibrium quantum many-body systems for the City University of New York graduate students. 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.