论文标题
超导镍的密切相关的掺杂孔载体：它们的位置，局部多体状态和低能量有效的汉密尔顿
Strongly correlated doped hole carriers in the superconducting nickelates: Their location, local many-body state, and low-energy effective Hamiltonian
论文作者
论文摘要
高温超导体的家庭最近欢迎了一个新成员：孔掺杂镍nd $ _ {0.8} $ sr $ _ {0.2} $ nio $ _2 $，$ \ sim $ \ sim $ 15K过渡温度。为了了解其新兴的低能行为和实验性能，一个直接的关键问题是，超导孔载体是否像在铜中一样驻留在氧气中，还是在大多数镍中居中。我们通过``（LDA+$ u $）+ED'方案回答了这个关键问题：从密度功能性LDA+$ u $计算中得出有效的孔载体相互作用的汉密尔顿，并通过精确的对角化来研究其本地多体状态。出乎意料的是，与大多数镍盐中发现的预期ni $^{2+} $旋转三个状态不同，两个孔的局部基态实际上是一个Ni-o旋转单孔状态，第二个孔中的第二个孔非常居住在氧气中。因此，出现的EV尺度模型类似于丘比特的模型，主张进一步的系统性实验比较。我们提出了这种意外结果的微观起源，即该材料中缺乏根尖的氧气，我们提出了一种增加超导温度的途径，并且在库酸酯中不存在可能的量子相变。
The families of high-temperature superconductors recently welcomed a new member: hole doped nickelate Nd$_{0.8}$Sr$_{0.2}$NiO$_2$ with a $\sim$15K transition temperature. To understand its emergent low-energy behaviors and experimental properties, an immediate key question is whether the superconducting hole carriers reside in oxygen as in the cuprates, or in nickel as in most nickelates. We answer this crucial question via a ``(LDA+$U$)+ED'' scheme: deriving an effective interacting Hamiltonian of the hole carriers from density functional LDA+$U$ calculation, and studying its local many-body states via exact diagonalization. Surprisingly, distinct from the expected Ni$^{2+}$ spin-triplet state found in most nickelates, the local ground state of two holes is actually a Ni-O spin-singlet state with second hole greatly residing in oxygen. The emerged eV-scale model therefore resembles that of the cuprates, advocating further systematic experimental comparisons. Tracing the microscopic origin of this unexpected result to the lack of apical oxygen in this material, we proposed a route to increase superconducting temperature, and a possible quantum phase transition absent in the cuprates.
