Interplay of two $E_g$ orbitals in Superconducting La$_3$Ni$_2$O$_7$ Under Pressure
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arXiv
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| Auteurs principaux: | , , , |
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| Format: | Preprint |
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2023
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| _version_ | 1866910611571474432 |
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| author | Lu, Chen Pan, Zhiming Yang, Fan Wu, Congjun |
| author_facet | Lu, Chen Pan, Zhiming Yang, Fan Wu, Congjun |
| contents | The discovery of high-$T_c$ superconductivity (SC) in La$_3$Ni$_2$O$_7$ (LNO) has aroused a great deal of interests. Previously, it was proposed that the Ni-$3d_{z^2}$ orbital is crucial to realize the high-$T_c$ SC in LNO: The preformed Cooper pairs therein acquire coherence via hybridization with the $3d_{x^2-y^2}$ orbital to form the SC. However, we held a different viewpoint that the interlayer pairing $s$-wave SC is induced by the $3d_{x^2-y^2}$ orbital, driven by the strong interlayer superexchange interaction. To include effects from both $E_g$-orbitals , we establish a two-orbital bilayer $t$-$J$ model. Our calculations reveal that due to the no-double-occupancy constraint, the $3d_{x^2-y^2}$ band and the $3d_{z^2}$ bonding band are flattened by a factor of about 2 and 10, respectively, which is consistent with recent angle-resolved-photo-emission-spectroscopy measurements. Consequently, a high temperature SC can be hardly induced in the $3d_{z^2}$-orbital due to the difficulty to develop phase coherence. However, it can be easily achieved by the $3d_{x^2-y^2}$ orbital under realistic interaction strength. With electron doping, the $3d_{z^2}$-band gradually dives below the Fermi level, but $T_c$ continues to enhance, suggesting that it is not necessary for the high-$T_c$ SC in LNO. With hole doping, $T_c$ initially drops and then rises, accompanied by the crossover from the BCS to BEC-type superconducting transitions. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2310_02915 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Interplay of two $E_g$ orbitals in Superconducting La$_3$Ni$_2$O$_7$ Under Pressure Lu, Chen Pan, Zhiming Yang, Fan Wu, Congjun Superconductivity The discovery of high-$T_c$ superconductivity (SC) in La$_3$Ni$_2$O$_7$ (LNO) has aroused a great deal of interests. Previously, it was proposed that the Ni-$3d_{z^2}$ orbital is crucial to realize the high-$T_c$ SC in LNO: The preformed Cooper pairs therein acquire coherence via hybridization with the $3d_{x^2-y^2}$ orbital to form the SC. However, we held a different viewpoint that the interlayer pairing $s$-wave SC is induced by the $3d_{x^2-y^2}$ orbital, driven by the strong interlayer superexchange interaction. To include effects from both $E_g$-orbitals , we establish a two-orbital bilayer $t$-$J$ model. Our calculations reveal that due to the no-double-occupancy constraint, the $3d_{x^2-y^2}$ band and the $3d_{z^2}$ bonding band are flattened by a factor of about 2 and 10, respectively, which is consistent with recent angle-resolved-photo-emission-spectroscopy measurements. Consequently, a high temperature SC can be hardly induced in the $3d_{z^2}$-orbital due to the difficulty to develop phase coherence. However, it can be easily achieved by the $3d_{x^2-y^2}$ orbital under realistic interaction strength. With electron doping, the $3d_{z^2}$-band gradually dives below the Fermi level, but $T_c$ continues to enhance, suggesting that it is not necessary for the high-$T_c$ SC in LNO. With hole doping, $T_c$ initially drops and then rises, accompanied by the crossover from the BCS to BEC-type superconducting transitions. |
| title | Interplay of two $E_g$ orbitals in Superconducting La$_3$Ni$_2$O$_7$ Under Pressure |
| topic | Superconductivity |
| url | https://arxiv.org/abs/2310.02915 |