We present high-quality angle-resolved photoemission (ARPES) and density functional theory calculations (DFT+U) of SmCoIn₅. We find broad agreement with previously published studies of LaCoIn₅ and CeCoIn₅^1,2, confirming that the Sm 4f electrons are mostly localized. Nevertheless, our model is consistent with an additional delocalized Sm component, stemming from hybridization between the 4f electrons and the metallic bands at “hot spot” positions in the Brillouin zone. The dominant hot spot, called γ_Z, is similar to a source of delocalized f states found in previous experimental and theoretical studies of CeCoIn₅^1,3. In this work, we identify and focus on the role of the Co d states in exploring the relationship between heavy quasiparticles and the magnetic interactions in SmCoIn₅, which lead to a magnetically ordered ground state from within an intermediate valence scenario^4,5,6. Specifically, we find a globally flat band consisting of Co d states near E = − 0.7 eV, indicating the possibility of enhanced electronic and magnetic interactions in the “115” family of materials through localization in the Co layer, and we discuss a possible origin in geometric frustration. We also show that the delocalized Sm 4f states can hybridize directly with the Co 3d_xz/3d_yz orbitals, which occurs in our model at the Brillouin zone boundary point R in a band that is locally flat and touches the Fermi level from above. Our work identifies microscopic ingredients for additional magnetic interactions in the “115” materials beyond the RKKY mechanism, and strongly suggests that the Co d bands are an important ingredient in the formation of both magnetic and superconducting ground states.

_{我们提出了 SmCoIn 5}的高质量角分辨光电（ARPES）和密度泛函理论计算（DFT+U）。我们发现与之前发表的 LaCoIn ₅和 CeCoIn ₅ ^1,2研究结果广泛一致，证实 Sm 4 f电子大部分是局域化的。尽管如此，我们的模型与额外的离域 Sm 成分是一致的，该成分源于 4 f电子与布里渊区“热点”位置处的金属带之间的杂化。主要热点称为γ _Z，类似于之前在 CeCoIn ₅ ^{1,3的实验和理论研究中发现的离域}f态源。在这项工作中，我们确定并重点关注 Co d态在探索重准粒子与 SmCoIn ₅中磁相互作用之间的关系中的作用，这导致从中间价态^4,5,6中产生磁有序基态。具体来说，我们发现了一个由E = − 0.7 eV附近的Co d态组成的全局平坦能带 ，表明“115”族材料中通过定位在 Co 层中增强电子和磁相互作用的可能性，并且我们讨论了可能的起源在几何挫败感中。我们还表明，离域 Sm 4 f态可以直接与 Co 3 d _{x z} /3 d _{y z}轨道杂化，这发生在我们的模型中布里渊区边界点R处，位于局部平坦并接触费米的能带中从上面看水平。我们的工作确定了“115”材料中超出 RKKY 机制的额外磁相互作用的微观成分，并强烈表明 Co d带是磁性和超导基态形成的重要成分。