Quantum Materials for Energy Efficient Neuromorphic Computing: Defective La<sub>1-x</sub>Sr<sub>x</sub>CoO<sub>3-d</sub>
ORAL
Abstract
We present a first principle study of La1-xSrxCoO3-d, a promising candidate material to build devices for neuromorphic computers. In particular we investigate how the generation of oxygen vacancies can drive a metal-to-insulator transition in the system, with focus on the interplay between structural, electronic and magnetic properties.
Using DFT+U and the Quantum Espresso package (https://github.com/QEF/q-e/releases/tag/qe-6.1.0), we found that increasing the oxygen vacancy concentration from 0 % to ~11 % leads to a change of the cobalt’s oxidation state and of the magnetic state of the system, accompanied by a variation of the octahedral tilt angle and lattice parameters. Altogether these changes determine the opening of the fundamental gap. For x = 0 (no Sr doping) and d varying from 0 to 0.5, we observe a structural transformation from a perovskite phase (semiconductor) to a brownmillerite phase (insulator), consistent with experiments.
Using DFT+U and the Quantum Espresso package (https://github.com/QEF/q-e/releases/tag/qe-6.1.0), we found that increasing the oxygen vacancy concentration from 0 % to ~11 % leads to a change of the cobalt’s oxidation state and of the magnetic state of the system, accompanied by a variation of the octahedral tilt angle and lattice parameters. Altogether these changes determine the opening of the fundamental gap. For x = 0 (no Sr doping) and d varying from 0 to 0.5, we observe a structural transformation from a perovskite phase (semiconductor) to a brownmillerite phase (insulator), consistent with experiments.
*This work was supported as part of the Quantum-Materials for Energy Efficient Neuromorphic-Computing (Q-MEEN-C), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0019273.
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Presenters
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Shenli Zhang
- University of Chicago