Unraveling the origin of Kondo-like behavior in the 3d-electron heavy-fermion compound YFe2Ge2

• 成果类型: Article
• 署名作者: Xu, Bing; Liu, Rui; Wo, Hongliang; Liao, Zhiyu; Yi, Shaohui; Li, Chunhong; Zhao, Jun; Qiu, Xianggang; Yin, Zhiping; Bernhard, Christian
• 署名单位: Chinese Academy of Sciences; Institute of Physics, CAS; Chinese Academy of Sciences; University of Chinese Academy of Sciences, CAS; University of Fribourg; University of Fribourg; Beijing Normal University; Fudan University; Fudan University; Beijing Normal University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-10881
• DOI: 10.1073/pnas.2401430121
• 发表日期: 2024-09-24
• 关键词: unconventional superconductivity; magnetism; electron; DYNAMICS

摘要

The heavy fermion (HF) state of d-electron systems is of great current interest since it exhibits various exotic phases and phenomena that are reminiscent of the Kondo effect in f-electron HF systems. Here, we present a combined infrared spectroscopy and first-principles band structure calculation study of the 3d-electron HF compound YFe2Ge2. The infrared response exhibits several charge-dynamical hallmarks of HF and a corresponding scaling behavior that resemble those of the f-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 (O similar to 50 meV) and a strongly enhanced quasiparticle effective mass. Moreover, the temperature dependence of the infrared response indicates a crossover around T & lowast; similar to 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 YFe2Ge2 is distinct from the Kondo scenario of the f-electron HF compounds and even from that of the d-electron iron-arsenide superconductor KFe2As2. For the latter, the HF state is driven by orbital-selective correlations due to a strong Hund's coupling. Instead, for YFe2Ge2 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 FeGe-Fe hoppings, band hybridization involving Fe 3d and Y 4d electrons, and electron correlations. This highlights that rather different mechanisms can be at the heart of the HF state in d-electron systems.