The recent discovery of ambient-pressure superconductivity with a critical temperature Tc exceeding 40 K in La_(3)Ni_(2)O_(7) thin films represents a significant advancement in the field of nickelate superconductivity...The recent discovery of ambient-pressure superconductivity with a critical temperature Tc exceeding 40 K in La_(3)Ni_(2)O_(7) thin films represents a significant advancement in the field of nickelate superconductivity.Motivated by recent experimental reports,we investigate an 11-band d–p Hubbard model with tight-binding parameters derived from ab initio calculations,employing large-scale determinant quantum Monte Carlo and cellular dynamical mean-field theory.Our results show that the dominant superexchange couplings in the La_(3)Ni_(2)O_(7) thin films are substantially weaker than those in the bulk material at 29.5 GPa.Specifically,the out-of-plane antiferromagnetic correlation between the Ni-d_(3z^(2)–r^(2)) orbitals is reduced by approximately 27%in the film,whereas the in-plane magnetic correlations remain largely unaffected.We further evaluate the corresponding antiferromagnetic coupling constants,J_(⊥) and J_(||),within a perturbative framework.Regarding charge-transfer properties,we find that biaxial compressive strain in the films reduces the charge-transfer gap.We further resolve the orbital distribution of doped holes and electrons between the IP(Ni-d_(x^(2)–y^(2)) and O-p_(x)/p_(y))and OP(Ni-d_(3z^(2)–r^(2)) and O-p_(z))orbitals,revealing a pronounced particle–hole asymmetry.These findings lay the groundwork for constructing a low-energy t–J model for La_(3)Ni_(2)O_(7) films and provide key insights into the physical distinctions between thin-film and bulk bilayer nickelates.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.12494591,12494594,and 92565303)the National Key R&D Program of China (Grant No.2022YFA1402802)+2 种基金the Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices (Grant No.2022B1212010008)the Research Center for Magnetoelectric Physics of Guangdong Province (Grant No.2024B0303390001)the Guangdong Provincial Quantum Science Strategic Initiative (Grant No.GDZX2401010)。
文摘The recent discovery of ambient-pressure superconductivity with a critical temperature Tc exceeding 40 K in La_(3)Ni_(2)O_(7) thin films represents a significant advancement in the field of nickelate superconductivity.Motivated by recent experimental reports,we investigate an 11-band d–p Hubbard model with tight-binding parameters derived from ab initio calculations,employing large-scale determinant quantum Monte Carlo and cellular dynamical mean-field theory.Our results show that the dominant superexchange couplings in the La_(3)Ni_(2)O_(7) thin films are substantially weaker than those in the bulk material at 29.5 GPa.Specifically,the out-of-plane antiferromagnetic correlation between the Ni-d_(3z^(2)–r^(2)) orbitals is reduced by approximately 27%in the film,whereas the in-plane magnetic correlations remain largely unaffected.We further evaluate the corresponding antiferromagnetic coupling constants,J_(⊥) and J_(||),within a perturbative framework.Regarding charge-transfer properties,we find that biaxial compressive strain in the films reduces the charge-transfer gap.We further resolve the orbital distribution of doped holes and electrons between the IP(Ni-d_(x^(2)–y^(2)) and O-p_(x)/p_(y))and OP(Ni-d_(3z^(2)–r^(2)) and O-p_(z))orbitals,revealing a pronounced particle–hole asymmetry.These findings lay the groundwork for constructing a low-energy t–J model for La_(3)Ni_(2)O_(7) films and provide key insights into the physical distinctions between thin-film and bulk bilayer nickelates.
