Using a combination of local density functional theory and cluster exact diagonalization based dynamical mean field theory, we calculate many body electronic structures of several Mott insulating oxides including undoped high T_{c} materials. The dispersions of the lowest occupied electronic states are associated with the Zhang-Rice singlets in cuprates and with doublets, triplets, quadruplets and quintets in more general cases. Our results agree with angle resolved photoemission experiments including the decrease of the spectral weight of the Zhang--Rice band as it approaches k=0.
Cuprate materials, like those hosting high temperature superconductivity, represent a famous class of materials where the correlations between the strongly entangled charges and spins produce complex phase diagrams. Several years ago the Zhang-Rice singlet was proposed as a natural quasiparticle in hole-doped cuprates. The occurance and binding energy of this quasiparticle, consisting of a pair of bound holes with antiparallel spins on the same CuO$_4$ plaquette, depends on the local electronic interactions, which are fundamental quantities for understanding the physics of the cuprates. Here, …
We argue that tetragonal CuO (T-CuO) has the potential to finally settle long-standing modelling issues for cuprate physics. We compare the one-hole quasiparticle (qp) dispersion of T-CuO to that of cuprates, in the framework of the strongly-correlated ($U_{dd}\rightarrow \infty$) limit of the three-band Emery model. Unlike in CuO$_2$, magnetic frustration in T-CuO breaks the $C_4$ rotational symmetry and leads to strong deviations from the Zhang-Rice singlet picture in parts of the reciprocal space. Our results are consistent with angle-resolved photoemission spectroscopy data but in sharp co…
Doped Spin Ladder: Zhang-Rice Singlets or Rung-centred Holes?
我们建立了一个单掺杂自旋梯的电荷转移模型，该模型与Sr $_{3}$ Ca $_{11}$ Cu $_{24}$ O $_{41}$中耦合自旋梯的本征掺杂平面有关。假设存在的实验观察到的电荷秩序在系统中，我们解决了模型使用Hartree-Fock近似。我们的研究结果表明，与最近的X射线吸收测量结果一致，相对于其他配置的掺杂空穴的张-赖斯单态的深刻的稳定性。
Unrevealing local magnetic and electronic correlations in the vicinity of charge carriers is crucial in order to understand rich physical properties in correlated electron systems. Here, using high-energy optical conductivity (up to 35 eV) as a function of temperature and polarization, we observe a surprisingly strong spin polarization of the local spin singlet with enhanced ferromagnetic correlations between Cu spins near the doped holes in lightly hole-doped La$_{1.95}$Sr$_{0.05}$Cu$_{0.95}$Zn$_{0.05}$O$_{4}$. The changes of the local spin polarization manifest strongly in the temperature-de…
Superconductivity found in doped NdNiO$_2$ is puzzling as two local symmetries of doped NiO$_2$ layers compete, with presumably far-reaching implications for the involved mechanism: a cuprate-like regime with Zhang-Rice singlets {\cblue is replaced by local triplet states at realistic values of charge-transfer energy, which would suggest a rather different superconductivity scenario from high-$T_c$ cuprates}. We address this competition by investigating Ni$_4$O$_8$ clusters with periodic boundary conditions in the parameter range relevant for the superconducting nickelates. With increasing val…
Yamaji effect and quantum oscillation in Yang-Rice-Zhang model of underdoped cuprates
Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所）；University of Chinese Academy of Sciences（中国科学院大学）；Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences（中国科学院大学理论科学研究所）
Frustration from Localized Zhang-Rice States: A Unified Theory of Doping-Driven Magnetic Transitions in Cuprates
Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所）；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）；Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University（上海交通大学物理与天文学院人工结构与量子控制教育部重点实验室）
Visualizing the Zhang-Rice singlet, molecular orbitals and pair formation in cuprate
Tsinghua University（清华大学）；Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所）；New Cornerstone Science Laboratory（新基石科学实验室）；Frontier Science Center for Quantum Information（量子信息前沿科学中心）；Hefei National Laboratory（合肥国家实验室）
Electronic States and Excitation Spectra of Copper Oxides with Ladder and/or Chain
最近报道了具有梯形和共边链的铜氧化物（Sr，Ca）$_{14}$ Cu $_{24}$ O $_{41}$在压力下的超导电性。为了更好地理解超导机制，弄清自掺杂空穴的分布是至关重要的。通过离子模型和精确对角化方法对样品的电导率进行分析，证实了Ca取代Sr后，自掺杂空穴从链状结构转移到了梯状结构。我们还研究了各种铜氧化物中共边链的电子态，并导出了有效哈密顿量。讨论了Cu离子间的磁相互作用和Zhang-Rice单重态的跳跃能与Cu-O-Cu键角的关系。
Using the ab initio embedded DMFT (eDMFT) approach, we study the effect of long-range magnetic ordering on the spectral properties in the binary transition metal oxides, and find that the most significant changes appear in the momentum resolved spectral functions, which sharpen into quite well-defined bands in the antiferromagnetic (AFM) phase. The strongest change across the transition is found at the topmost valence band edge (VBE), which is commonly associated with the Zhang-Rice bound state. This VBE state strengthens in the AFM phase, but only for the minority spin component, which is sub…
The correlated electronic structure of the infinite-layer compounds NdNiO$_2$ and SrCuO$_2$ at stoichiometry and with finite hole doping is compared. Key differences are elucidated from an advanced first-principles many-body perspective. Contrary to the charge-transfer insulating cuprate, the self-doped nickelate remains non-insulating even for large interaction strength, though the Ni-$d_{x^2-y^2}$ spectral weight is also gapped in that limit. Hybridization between Ni$(3d)$ and Nd$(5d)$ is crucial for the appearance of the self-doping band. Upon realistic hole doping, Sr$_{1-y}$CuO$_2$ shows …
Temperature dependance of the tunneling density of states in sub-micron planar metal / oxide / graphene junctions
我们提出了亚微米金属/绝缘体/石墨烯平面隧道结的隧穿测量到室温。我们观察到了一个与栅极无关的能隙，这是以前只能通过低温STM观察到的。Zhang等人，4，627（2008）]。在150 K以上没有能隙出现，这比从公认的平均场模型[T. O. Wehling等人，Phys. Rev. Lett. 101，216803（2008）]。我们表明，考虑到一个额外的振动效应的面外声子软模式的间隙可能会消失，从测量温度远低于计算的$T_{c}$。
