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arXiv 2102.05060cond-mat.str-elcond-mat.supr-con
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电子-声子耦合诱导的反铁磁性

Antiferromagnetism induced by electron-phonon-coupling

Xun Cai, Zi-Xiang Li, Hong Yao

摘要:

反铁磁性(AF),如尼尔序,往往是密切相关的库仑相互作用,如哈伯德排斥在二维(2D)系统。二维Neel AF有序化是否可以由电子-声子耦合(EPC)主导引起还没有完全理解。在这里,通过采用数值精确的符号问题的自由量子蒙特卡罗(QMC)模拟,我们表明,光学Su-Schrieffer-Heeger(SSH)声子频率$ω$和EPC常数$λ$可以诱导AF有序的声子频率$ω>ω_c$的宽范围内。对于$ω<ω_c$,出现价键固体(VBS)有序,并且在$ω_c$处存在VBS和AF相之间的直接量子相变。AF有序的声子机制与SSH声子直接耦合电子跳跃的二级过程可以诱导有效的AF自旋交换有关。我们的结果将为理解关联量子材料中的AF有序提供新的思路。

英文摘要:

Antiferromagnetism (AF) such as Neel ordering is often closely related to Coulomb interactions such as Hubbard repulsion in two-dimensional (2D) systems. Whether Neel AF ordering in 2D can be dominantly induced by electron-phonon couplings (EPC) has not been completely understood. Here, by employing numerically-exact sign-problem-free quantum Monte Carlo (QMC) simulations, we show that optical Su-Schrieffer-Heeger (SSH) phonons with frequency $ω$ and EPC constant $λ$ can induce AF ordering for a wide range of phonon frequency $ω>ω_c$. For $ω<ω_c$, a valence-bond-solid (VBS) order appears and there is a direct quantum phase transition between VBS and AF phases at $ω_c$. The phonon mechanism of the AF ordering is related to the fact that SSH phonons directly couple to electron hopping whose second-order process can induce an effective AF spin exchange. Our results shall shed new lights to understanding AF ordering in correlated quantum materials.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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