Interlayer Coupling Driven High-Temperature Superconductivity in La$_3$Ni$_2$O$_7$ Under Pressure

• DOI: 10.48550/arxiv.2307.14965
• Publication Date: 2023-01-01
• Authors: Lu Chen; Zhiming Pan; Fan Yang; Congjun Wu
• Keywords: Superconductivity (cond-mat.supr-con); Condensed Matter - Strongly Correlated Electrons; Strongly Correlated Electrons (cond-mat.str-el); Condensed Matter - Superconductivity; FOS: Physical sciences

The newly discovered high-temperature superconductivity in La$_3$Ni$_2$O$_7$ under pressure has attracted a great deal of attentions. essential ingredient characterizing the electronic properties is bilayer NiO$_2$ planes coupled by interlayer bonding $3d_{z^2}$ orbitals through intermediate oxygen-atoms. In strong coupling limit, low energy physics described an intralayer antiferromagnetic spin-exchange interaction $J_{\parallel}$ between $3d_{x^2-y^2}$ and one $J_{\perp}$ orbitals. Taking into account Hund's rule on each site integrating out spin degree freedom, system reduces to single-orbital $t$-$J$ model based orbital. By employing slave-boson approach, self-consistent equations for pairing order parameters are solved. Near physically relevant $\frac{1}{4}$-filling regime (doping $\delta=0.3\sim 0.5$), tunes conventional single-layer $d$-wave superconducting state $s$-wave one. A could enhance inter-layer order, leading dramatically increased $T_c$. Interestingly, there exist finite which $s+id$ emerges.