Datta Sawani, Prakash Pandeya Ram, Bikash Dey Arka, Gloskovskii A, Schlueter C, Peixoto T R F, Singh Ankita, Thamizhavel A, Maiti Kalobaran
Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India.
Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany.
J Phys Condens Matter. 2023 Mar 28;35(23). doi: 10.1088/1361-648X/acc5c9.
We investigate the electronic structure of an antiferromagnetic Kondo lattice system CeAgAsemploying hard-ray photoemission spectroscopy. CeAgAs, an orthorhombic variant of HfCuSistructure, exhibits antiferromagnetic ground state, Kondo like resistivity upturn and compensation of magnetic moments at low temperatures. The photoemission spectra obtained at different photon energies suggest termination of the cleaved surface at cis-trans-As layers. The depth-resolved data show significant surface-bulk differences in the As and Ce core level spectra. The As 2bulk spectrum shows distinct two peaks corresponding to two different As layers. The peak at higher binding energy correspond to cis-trans-As layers and is weakly hybridized with the adjacent Ce layers. The As layers between Ce and Ag-layers possess close to trivalent configuration due to strong hybridization with the neighboring atoms and the corresponding feature appear at lower binding energy. Ce 3core level spectra show multiple features reflecting strong Ce-As hybridization and strong correlation. Intensepeak is observed in the surface spectrum while it is insignificant in the bulk. In addition, we observe a features at binding energy lower than the well-screened feature indicating the presence of additional interactions. This feature becomes more intense in the bulk spectra suggesting it to be a bulk property. Increase in temperature leads to a spectral weight transfer to higher binding energies in the core level spectra and a depletion of spectral intensity at the Fermi level as expected in a Kondo material. These results reveal interesting surface-bulk differences, complex interplay of intra- and inter-layer covalency, and electron correlation in the electronic structure of this novel Kondo lattice system.
我们利用硬射线光电子能谱研究了反铁磁近藤晶格体系CeAgAs的电子结构。CeAgAs是HfCuSi结构的正交变体，表现出反铁磁基态、近藤型电阻率上升以及低温下磁矩的补偿。在不同光子能量下获得的光电子能谱表明，解理表面终止于顺式-反式-As层。深度分辨数据显示，As和Ce芯能级谱存在显著的表面-体相差异。As 2体相谱显示出对应于两个不同As层的明显双峰。较高结合能处的峰对应于顺式-反式-As层，并且与相邻的Ce层弱杂化。由于与相邻原子的强杂化，Ce和Ag层之间的As层具有接近三价的构型，并且相应的特征出现在较低的结合能处。Ce 3芯能级谱显示出反映Ce-As强杂化和强关联的多个特征。在表面谱中观察到强烈的峰，而在体相中则不明显。此外，我们在结合能低于充分屏蔽特征处观察到一个特征，表明存在额外的相互作用。该特征在体相谱中变得更强，表明它是一种体相性质。温度升高导致芯能级谱中的光谱权重转移到更高的结合能，并且费米能级处的光谱强度耗尽，这在近藤材料中是预期的。这些结果揭示了这个新型近藤晶格体系电子结构中有趣的表面-体相差异、层内和层间共价性的复杂相互作用以及电子关联。
