论文标题
镍和铜层膜之间的相似性和差异在srtio $ _3 $底物上生长
Similarities and differences between nickelate and cuprate films grown on a SrTiO$_3$ substrate
论文作者
论文摘要
在Srtio $ _3 $上生长的SR掺杂NDNIO $ _2 $ _2 $ _2 $的超导性的最近发现，在非常规超导性中开始了一个新颖的领域。 To understand the similarities and differences between nickelate and cuprate layers on the same SrTiO$_3$ substrate, here based on the density functional theory we have systematically investigated the structural, electronic, and magnetic properties of NdNiO$_2$/SrTiO$_3$ and CaCuO$_2$/SrTiO$_3$ systems.我们的结果表明，对于NDNIO $ _2 $/srtio $ _3 $，晶格的重建很强，导致了极性膜，表面和界面NiO $ _2 $层呈现相反的位移。但是，对于cacuo $ _2 $/srtio $ _3 $，相同两个CuO $ _2 $层的扭曲朝着相同的方向。此外，我们发现这种失真近似与镍和丘陵薄膜的膜厚度范围无关。此外，我们还观察到与最近的文献一致，这是由极性不连续性引起的ndnio $ _2 $和srtio $ _3 $之间的界面上的二维电子气体。对于ndnio $ _2 $/srtio $ _3 $，二维电子气体在几层上扩展，而对于Cacuo $ _2 $/srtio $ _3 $，此电子重排在Cacuo $ _2 $和SRTIO $ $ _3 $之间的界面上非常本地化。在接口上发现的电子重建涉及ti $ 3d_ {xy} $状态的强大职业。在这两种情况下，从表面Ni或Cu层到Ti界面层都有明显的电子电荷转移。界面Ni和Cu层分别是孔和电子掺杂的。通过引入磁性和电子相关性，我们观察到Ni的$ d_ {3z^2-r^2} $轨道变得行动，而Cu的相同轨道保持双重占据，建立了对这些系统描述描述的清晰的两种和单方面的活性框架。
The recent discovery of superconductivity in Sr-doped NdNiO$_2$ films grown on SrTiO$_3$ started a novel field within unconventional superconductivity. To understand the similarities and differences between nickelate and cuprate layers on the same SrTiO$_3$ substrate, here based on the density functional theory we have systematically investigated the structural, electronic, and magnetic properties of NdNiO$_2$/SrTiO$_3$ and CaCuO$_2$/SrTiO$_3$ systems. Our results revealed a strong lattice reconstruction in the case of NdNiO$_2$/SrTiO$_3$, resulting in a polar film, with the surface and interfacial NiO$_2$ layers presenting opposite displacements. However, for CaCuO$_2$/SrTiO$_3$, the distortions of those same two CuO$_2$ layers were in the same direction. In addition, we found this distortion to be approximately independent of the studied range of film thickness for both the nickelate and cuprates films. Furthermore, we also observed a two-dimensional electron gas at the interface between NdNiO$_2$ and SrTiO$_3$, caused by the polar discontinuity, in agreement with recent literature. For NdNiO$_2$/SrTiO$_3$ the two-dimensional electron gas extends over several layers, while for CaCuO$_2$/SrTiO$_3$ this electronic rearrangement is very localized at the interface between CaCuO$_2$ and SrTiO$_3$. The electronic reconstruction found at the interface involves a strong occupation of the Ti $3d_{xy}$ state. In both cases, there is a significant electronic charge transfer from the surface Ni or Cu layers to the Ti interface layer. The interfacial Ni and Cu layer is hole and electron doped, respectively. By introducing magnetism and electronic correlation, we observed that the $d_{3z^2-r^2}$ orbital of Ni becomes itinerant while the same orbital for Cu remains doubly occupied, establishing a clear two- vs one-orbital active framework for the description of these systems.
