Papers
Topics
Authors
Recent
Gemini 2.5 Flash
Gemini 2.5 Flash
134 tokens/sec
GPT-4o
9 tokens/sec
Gemini 2.5 Pro Pro
47 tokens/sec
o3 Pro
4 tokens/sec
GPT-4.1 Pro
38 tokens/sec
DeepSeek R1 via Azure Pro
28 tokens/sec
2000 character limit reached

Type II t-J model and shared antiferromagnetic spin coupling from Hund's rule in superconducting La$_3$Ni$_2$O$_7$ (2307.15706v3)

Published 28 Jul 2023 in cond-mat.str-el and cond-mat.supr-con

Abstract: Recently, a 80 K superconductor was discovered in La$3$Ni$_2$O$_7$ under high pressure. Density function theory (DFT) calculations identify $d{x2-y2}$, $d_{z2}$ as the active orbitals on the bilayer square lattice with a $d{8-x}$ configuration of of Ni per site. One naive expectation is to describe this system in terms of a two-orbital t-J model. However, we emphasize the importance of Hund's coupling $J_H$ and the $x=0$ limit should be viewed as a spin-one Mott insulator. Especially, the significant Hund's coupling shares the inter-layer super-exchange $J_\perp$ of the $d_{z2}$ orbital to the $d_{x2-y2}$ orbital, an effect that cannot be captured by conventional perturbation or mean-field approaches. In this study, we first explore the limit where the $d_{z2}$ orbital is Mott localized, dealing with a one-orbital bilayer t-J model focused on the $d_{x2-y2}$ orbital. Notably, we find that strong inter-layer pairing survives up to $x=0.5$ hole doping driven by the transmitted $J_\perp$, which explains the existence of a high Tc superconductor in the experiment at this doping level. Next, we uncover the more realistic situation where the $d_{z2}$ orbital is slightly hole-doped and cannot be simply integrated out. We take the $J_H\rightarrow +\infty$ limit and propose a type II t-J model with four \textit{spin-half} singlon ($d7$) states and three \textit{spin-one} doublon ($d8$) states. Employing a parton mean-field approach, we recover similar results as in the one-orbital t-J model, but now with the effect of the $J_\perp$ automatically generated. We propose future experiments to electron dope the system to further enhance $T_c$.

Definition Search Book Streamline Icon: https://streamlinehq.com
References (6)
  1. Y. Cao and Y.-f. Yang, arXiv preprint arXiv:2307.06806  (2023).
  2. Y.-H. Zhang and A. Vishwanath, Physical Review Research 2, 023112 (2020).
  3. Y.-H. Zhang and Z. Zhu, Physical Review B 103, 115101 (2021).
  4. Y.-H. Zhang and A. Vishwanath, Physical Review B 106, 045103 (2022).
  5. C. Lu, Z. Pan, F. Yang,  and C. Wu, “Interlayer coupling driven high-temperature superconductivity in la33{}_{3}start_FLOATSUBSCRIPT 3 end_FLOATSUBSCRIPTni22{}_{2}start_FLOATSUBSCRIPT 2 end_FLOATSUBSCRIPTo77{}_{7}start_FLOATSUBSCRIPT 7 end_FLOATSUBSCRIPT under pressure,”  (2023), arXiv:2307.14965 [cond-mat.supr-con] .
  6. H. Yang, H. Oh,  and Y.-H. Zhang, “Strong pairing from doping-induced feshbach resonance and second fermi liquid through doping a bilayer spin-one mott insulator: application to la33{}_{3}start_FLOATSUBSCRIPT 3 end_FLOATSUBSCRIPTni22{}_{2}start_FLOATSUBSCRIPT 2 end_FLOATSUBSCRIPTo77{}_{7}start_FLOATSUBSCRIPT 7 end_FLOATSUBSCRIPT,”  (2023b), arXiv:2309.15095 [cond-mat.str-el] .
Citations (21)

Summary

We haven't generated a summary for this paper yet.