论文标题
提议在散装无限层镍中的纹理旋转单线订购
Proposed ordering of textured spin singlets in a bulk infinite layer nickelate
论文作者
论文摘要
无限层结构镍$ _2 $ nio $ _2 $（AGSE）$ _ 2 $（BNOAS），带有$ d^8 $ ni ions和具有相关密度功能方法的特殊敏感性$χ（t）$。计算的覆盖特征是违反了洪德的规则，结合完整但非常规的旋转轨道极化，导致意外的低旋转$^1b_1 $，“ off-diagonal Singlet”（ODS）（ODS）（ODS）（ODS）质感，由$ d_ {x^2-y^2}^2 Y^2}^upOrlow $ d_ { $ d_ {z^2}^{\ downarrow} $ spins。这种非常规配置的能量低于常规高旋转或低自旋替代方案。电子过渡是在关键的Ni-O分离处获得的$ d_c^{ni-o} = $2.03Å，与之相比，Ni在Square Planar Nio $ _2 $化合物中变得磁性。我们提出了$ t_ {m} $ = 130 K $χ（t）$ in $χ（t）$ = 130 K的签名的场景，而没有任何curie-weiss背景（无时刻）调用Ni $ d^8 $部分的订购，这些部分很大程度上是这个广义的Kondo Singlet。该系统的基本物理是由“ Kondo” $ d_ {z^2} $旋转的近孔筛模型（2d Kondo项链）建模的，并耦合到$ d_ {x^2-y^2} $ spin本身与邻近的层中相邻的层中相邻的层。观察到的磁性位置将BNOA置于近托筛模型的量子临界点之下，从而实现了先前未报告的远程有序的近距离弱弱抗铁磁性相。我们提出了电子掺杂实验，该实验将使系统朝着$ d^{9-δ} $配置和可能的超导率，与最近报道的Ba $ _2 $ _2 $ cuo $ _ {3.2} $相似，该超导导在73 k处。
The infinite-layer structure nickelate Ba$_2$NiO$_2$(AgSe)$_2$ (BNOAS) with $d^8$ Ni ions and a peculiar susceptibility $χ(T)$ is studied with correlated density functional methods. The overriding feature of the calculations is violation of Hund's rule coupled with complete but unconventional spin-orbital polarization, leading to an unexpected low spin $^1B_1$, "off-diagonal singlet" (ODS) textured by an internal orbital structure of compensating $d_{x^2-y^2}^{\uparrow}$ and $d_{z^2}^{\downarrow}$ spins. This unconventional configuration has lower energy than conventional high-spin or low-spin alternatives. An electronic transition is obtained at a critical Ni-O separation $d_c^{Ni-O}=$2.03 Å, above which Ni becomes magnetic in square planar NiO$_2$ compounds. We propose scenarios for the signature of magnetic reconstruction in $χ(T)$ at $T_{m}$=130 K without any Curie-Weiss background (no moment) that invoke ordering of Ni $d^8$ moieties that are largely this generalized Kondo singlet. The underlying physics of this system is modeled by a Kondo sieve model (2D Kondo necklace) of a "Kondo" $d_{z^2}$ spin on each site, coupled to a $d_{x^2-y^2}$ spin that is itself strongly coupled to neighboring like-spins within the layer. The observed magnetic order places BNOAS below the quantum critical point of the Kondo sieve model, providing a realization of the previously unreported long-range ordered near-singlet weak antiferromagnetic phase. We propose electron doping experiments that would drive the system toward a $d^{9-δ}$ configuration and possible superconductivity with similarity to the recently reported Ba$_2$CuO$_{3.2}$ that superconducts at 73 K.
