Revisiting the Bi<sub>2</sub>Sr<sub>2</sub>CaCu<sub>2</sub>O<sub>8+x</sub> crystal and electronic structure by first principle calculations
ORAL
Abstract
The bismuth strontium calcium copper oxide (BSCCO) is one of the most intensively studied copper-based superconductors. The bilayered crystal structure, superconductivity above liquid nitrogen temperature, and exclusion of rare-earth elements make the BSCCO family important for both scientific research and applications. However, finding an accurate theoretical description of BSCCO is nontrivial because of the complicated supercell resulting from the crystal structural modulation [1] and the non-stoichiometric oxygen content observed in most samples in experiments.
In this work, we use density functional theory (DFT) to optimize the structural distortion and oxygen dopant positions in BSCCO, and revisit the electronic structure based on our crystal prediction. Our predictions of structural modulations and additional oxygen dopant positions match the scanning transmission electron microscopy (STEM) measurement results [2]. In particular, we demonstrate insulating bismuth bands as a direct result of optimized Bi-O layer distortion, which explains the absence of bismuth Fermi surface in all experiments regardless of doping level. In contrast, previous DFT studies [2-4] required an added amount of hole doping to get rid of the finite bismuth density of states at the Fermi level predicted for undoped BSCCO. Based on the optimized crystal structure, we also reproduce shadow bands on the Fermi surface observed in angle-resolved photoemission spectroscopy (ARPES) [5]. By capturing the dominant properties of the crystal and electronic structure in BSCCO under a first principle framework, our work can serve as a useful platform for future theoretical modeling and superconductor engineering.
References
[1] Yu et al., npj Quantum Materials 5, 46 (2020)
[2] Song et al., Adv. Funct. Mater. 29, 1903843 (2019)
[3] He et al., Phys. Rev. Lett. 96, 197002 (2006)
[4] Lin et al., Phys. Rev. Lett. 96, 097001 (2006)
[5] Mans et al., Phys. Rev. Lett. 96, 107007 (2006)
In this work, we use density functional theory (DFT) to optimize the structural distortion and oxygen dopant positions in BSCCO, and revisit the electronic structure based on our crystal prediction. Our predictions of structural modulations and additional oxygen dopant positions match the scanning transmission electron microscopy (STEM) measurement results [2]. In particular, we demonstrate insulating bismuth bands as a direct result of optimized Bi-O layer distortion, which explains the absence of bismuth Fermi surface in all experiments regardless of doping level. In contrast, previous DFT studies [2-4] required an added amount of hole doping to get rid of the finite bismuth density of states at the Fermi level predicted for undoped BSCCO. Based on the optimized crystal structure, we also reproduce shadow bands on the Fermi surface observed in angle-resolved photoemission spectroscopy (ARPES) [5]. By capturing the dominant properties of the crystal and electronic structure in BSCCO under a first principle framework, our work can serve as a useful platform for future theoretical modeling and superconductor engineering.
References
[1] Yu et al., npj Quantum Materials 5, 46 (2020)
[2] Song et al., Adv. Funct. Mater. 29, 1903843 (2019)
[3] He et al., Phys. Rev. Lett. 96, 197002 (2006)
[4] Lin et al., Phys. Rev. Lett. 96, 097001 (2006)
[5] Mans et al., Phys. Rev. Lett. 96, 107007 (2006)
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Presenters
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Zheting Jin
Yale University
Authors
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Zheting Jin
Yale University
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Sohrab Ismail-Beigi
Yale University