CAREER: Transport and optical properties of spin-compensated materials for next-generation non-volatile memory devices

About This Grant

NONTECHNICAL SUMMARY This award supports theoretical research on antiferromagnets, where no net magnetization shows up even when the material has an ordered underlying magnetic structure. Such hidden magnetic orders typically respond to external stimuli ~1,000 times faster than those in regular magnets, making them an intriguing candidate for future information processing devices with ultrafast response speed and low power consumption. One major challenge of such efforts is to identify the detection and manipulation methods of the hidden, compensated spin order using means that are available in a typical device setup. With the support of this CAREER award, the PI and their research team will address this issue by integrating the frontier developments of computational methods and quantum theory, enabling robust predictions and in-depth understanding of material behaviors under various perturbations, including electric currents, applied voltages and laser pulses. The outcomes of this project may enable new memory and computing technologies that are much faster than the conventional ones, whereas the corresponding power consumption can be dramatically reduced. Once achieved, these new technologies may create new opportunities in many digital solutions that are essential to our everyday life, including smartphones, personal computers, data centers and artificial intelligence services. This award also supports efforts contributing to the development of US STEM workforce through a series of new educational and extracurricular outreach efforts. Particularly, the award will support (i) the PI’s new topological physics course at Georgetown University for both undergraduate and graduate students; (ii) new lectures and interactive displays in USA Science and Engineering Festival at Washington DC; and (iii) new videos communicating the frontier developments of topological materials to the general public. TECHNICAL SUMMARY This award supports theoretical research on the transport and optical responses of antiferromagnets using density-functional theory, dynamic mean-field theory and Keldysh nonequilibrium Green’s functions. These investigations will generate the understanding of the linear response of antiferromagnets in the forms of bulk, thin films and devices of mesoscopic scales, particularly focusing on the transport and optical behaviors due to the lifted Kramers degeneracy. Activities supported by this award include (i) establishing the quasiparticle tight-binding models in antiferromagnets considering the electron-disorder interaction within the dynamic mean-field theory; (ii) creating a new numerical method that can adaptively and robustly resolve the topological and geometric features of the quasiparticle spectra; and (iii) investigation of the coherent transport of the quasiparticles in a tunnel junction setup, focusing on tunneling resistance and the spin torque. Outcomes of these activities will be integrated into a new open-domain package `QuantumGeom’, containing the new numerical methods that are useful for the research of general topological materials. This award also supports efforts contributing to the development of US STEM workforce through a series of new educational and extracurricular outreach efforts. Particularly, the award will support (i) the PI’s new topological physics course at Georgetown University for both undergraduate and graduate students; (ii) new lectures and interactive displays in USA Science and Engineering Festival at Washington DC; and (iii) new videos communicating the frontier developments of topological materials to the general public. 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.