Consiglio A, Gatti G, Martino E, Moreschini L, Johannsen J C, Prša K, Freeman P G, Sheptyakov D, Rønnow H M, Scopelliti R, Magrez A, Forró L, Schmitt C, Jovic V, Jozwiak C, Bostwick A, Rotenberg E, Hofmann T, Thomale R, Sangiovanni G, Di Sante D, Greiter M, Grioni M, Moser S
Institut für Theoretische Physik und Astrophysik and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, 97074 Würzburg, Germany.
Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Phys Rev Lett. 2024 Mar 22;132(12):126502. doi: 10.1103/PhysRevLett.132.126502.
LiCu_{3}O_{3} is an antiferromagnetic mixed valence cuprate where trilayers of edge-sharing Cu(II)O (3d^{9}) are sandwiched in between planes of Cu(I) (3d^{10}) ions, with Li stochastically substituting Cu(II). Angle-resolved photoemission spectroscopy (ARPES) and density functional theory reveal two insulating electronic subsystems that are segregated in spite of sharing common oxygen atoms: a Cu d_{z^{2}}/O p_{z} derived valence band (VB) dispersing on the Cu(I) plane, and a Cu 3d_{x^{2}-y^{2}}/O 2p_{x,y} derived Zhang-Rice singlet (ZRS) band dispersing on the Cu(II)O planes. First-principle analysis shows the Li substitution to stabilize the insulating ground state, but only if antiferromagnetic correlations are present. Li further induces substitutional disorder and a 2D electron glass behavior in charge transport, reflected in a large 530 meV Coulomb gap and a linear suppression of VB spectral weight at E_{F} that is observed by ARPES. Surprisingly, the disorder leaves the Cu(II)-derived ZRS largely unaffected. This indicates a local segregation of Li and Cu atoms onto the two separate corner-sharing Cu(II)O_{2} sub-lattices of the edge-sharing Cu(II)O planes, and highlights the ubiquitous resilience of the entangled two hole ZRS entity against impurity scattering.
LiCu₃O₃是一种反铁磁混合价铜酸盐，其中边缘共享的Cu(II)O（3d⁹）三层夹在Cu(I)（3d¹⁰）离子平面之间，Li随机取代Cu(II)。角分辨光电子能谱（ARPES）和密度泛函理论揭示了两个绝缘电子子系统，尽管共享共同的氧原子，但它们是分离的：一个由Cu dₓ²₋y²/O 2pₓ,y衍生的价带（VB）在Cu(I)平面上色散，以及一个由Cu 3dₓ²₋y²/O 2pₓ,y衍生的张-赖斯单重态（ZRS）带在Cu(II)O平面上色散。第一性原理分析表明，Li取代能稳定绝缘基态，但前提是存在反铁磁关联。Li进一步诱导了替代无序和电荷传输中的二维电子玻璃行为，这反映在一个大的530 meV库仑能隙以及ARPES观察到的费米能级处VB光谱权重的线性抑制上。令人惊讶的是，这种无序对源自Cu(II)的ZRS影响不大。这表明Li和Cu原子在边缘共享的Cu(II)O平面的两个单独的角共享Cu(II)O₂子晶格上发生了局部分离，并突出了纠缠的双空穴ZRS实体对杂质散射普遍存在的弹性。
