Unraveling the origin of Kondo-like behavior in the 3 d -electron heavy-fermion compound YFe 2 Ge 2
Year: 2024
Type: article
Abstract: The heavy fermion (HF) state of [Formula: see text]-electron systems is of great current interest since it exhibits various exotic phases and phenomena that are reminiscent of the Kondo effect in [Formula: see text]-electron HF systems. Here, we present a combined infrared spectroscopy and first-principles band structure calculation study of the [Formula: see text]-electron HF compound YFe[Formula: see text]Ge[Formula: see text]. The infrared response exhibits several charge-dynamical hallmarks of HF and a corresponding scaling behavior that resemble those of the [Formula: see text]-electron HF systems. In particular, the low-temperature spectra reveal a dramatic narrowing of the Drude response along with the appearance of a hybridization gap ([Formula: see text] 50 meV) and a strongly enhanced quasiparticle effective mass. Moreover, the temperature dependence of the infrared response indicates a crossover around [Formula: see text] 100 K from a coherent state at low temperature to a quasi-incoherent one at high temperature. Despite of these striking similarities, our band structure calculations suggest that the mechanism underlying the HF behavior in YFe[Formula: see text]Ge[Formula: see text] is distinct from the Kondo scenario of the [Formula: see text]-electron HF compounds and even from that of the [Formula: see text]-electron iron-arsenide superconductor KFe[Formula: see text]As[Formula: see text]. For the latter, the HF state is driven by orbital-selective correlations due to a strong Hund's coupling. Instead, for YFe[Formula: see text]Ge[Formula: see text] the HF behavior originates from the band flatness near the Fermi level induced by the combined effects of kinetic frustration from a destructive interference between the direct Fe-Fe and indirect Fe-Ge-Fe hoppings, band hybridization involving Fe [Formula: see text] and Y [Formula: see text] electrons, and electron correlations. This highlights that rather different mechanisms can be at the heart of the HF state in [Formula: see text]-electron systems.
Authors: Bing Xu, Rui Liu, Hongliang Wo, Zhiyu Liao, Shaohui Yi, Chunhong Li, Jun Zhao, Xianggang Qiu, Zhiping Yin, Christian Bernhard
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Funders: National Science Foundation, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, National Natural Science Foundation of China, Beijing Normal University, National Key Research and Development Program of China, Fundamental Research Funds for the Central Universities
Awards: G1262583917, G1767790239, G2485993052, 强关联拓扑材料的理论研究和计算设计, G4076842215, Superconductivity, magnetism and unconventional charge dynamics of high temperature superconductors, oxide thin films and heterostructures, G5599649393, G628552264, Terahertz and Infrared vortex beam spectroscopy of quantum materials, G8087225627, G903802937, G993971353
OpenAlex ID: W4402626491