Pairing mechanism and superconductivity in 1313 phase La$_3$Ni$_2$O$_7$

Cui-Qun Chen; Ming Zhang; Fan Yang; Dao-Xin Yao

doi:10.1088/0256-307X/43/7/070711

paper

Pairing mechanism and superconductivity in 1313 phase La $_{3}$ Ni $_{2}$ O $_{7}$

arXiv:2604.21533 · doi:10.1088/0256-307X/43/7/070711

Abstract

Recently, the observation of superconductivity (SC) with $T_{c}$ $\approx$ 3.6 K in the pressurized 1313 La $_{3}$ Ni $_{2}$ O $_{7}$ has attracted considerable interest. Here, we systematically investigate the electronic properties and superconducting mechanism of 1313 La $_{3}$ Ni $_{2}$ O $_{7}$ using density functional theory plus dynamical mean-field theory (DFT+DMFT) and random phase approximation (RPA). Our DFT+DMFT calculations reveal that the single-layer (SL) subsystem exhibits nearly insulating behavior, with the $d_{z^{2}}$ orbital showing Mott physics, while the trilayer (TL) subsystem remains metallic. This indicates that SC primarily resides in the TL subsystem, whose Ni- $e_{g}$ orbitals are found to be hole-doped relative to bulk La $_{4}$ Ni $_{3}$ O $_{10}$ . Based on DFT+DMFT-derived low-energy Hamiltonian, RPA-based analysis yields an $s^{\pm}$ -wave pairing symmetry within the TL subsystem. Importantly, we identify two key factors that contribute to the significant suppression of $T_{c}$ in 1313 La $_{3}$ Ni $_{2}$ O $_{7}$ compared to bulk La $_{4}$ Ni $_{3}$ O $_{10}$ . First, the hole doping in the TL subsystem, as established by DMFT, leads to a decreased pairing strength, as confirmed by RPA calculations -- a trend resembling that in bulk La $_{4}$ Ni $_{3}$ O $_{10}$ . Second, the SL subsystem acts as a bridge connecting adjacent superconducting TL subsystems, thereby forming an S-N-S Josephson junction. The resulting interlayer Josephson coupling governs the phase coherence between TL subsystems and further suppresses the global $T_{c}$ . Combinedly, our findings suggest that the high- $T_{c}$ phase in the RP La $_{3}$ Ni $_{2}$ O $_{7}$ family should be attributed to the 2222 La $_{3}$ Ni $_{2}$ O $_{7}$ rather than the 1313 La $_{3}$ Ni $_{2}$ O $_{7}$ .

6 pages, 5 figures

Pairing mechanism and superconductivity in 1313 phase La3​Ni2​O7​

Abstract

References in corpus (3)

Pairing mechanism and superconductivity in 1313 phase La $_{3}$ Ni $_{2}$ O $_{7}$