{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,25]],"date-time":"2026-09-25T14:30:16Z","timestamp":1790346616084,"version":"4.1.0"},"reference-count":72,"publisher":"National Academy of Sciences","issue":"39","license":[{"start":{"date-parts":[[2024,9,19]],"date-time":"2024-09-19T00:00:00Z","timestamp":1726704000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"MOST | National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["12274442"],"award-info":[{"award-number":["12274442"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012166","name":"MOST | National Key Research and Development Program of China","doi-asserted-by":"publisher","award":["2022YFA1403901"],"award-info":[{"award-number":["2022YFA1403901"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"MOST | National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["12074041"],"award-info":[{"award-number":["12074041"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001711","name":"Swiss National Science Foundation","doi-asserted-by":"crossref","award":["200020-172611"],"award-info":[{"award-number":["200020-172611"]}],"id":[{"id":"10.13039\/501100001711","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/501100001711","name":"Swiss National Science Foundation","doi-asserted-by":"crossref","award":["200021-214905"],"award-info":[{"award-number":["200021-214905"]}],"id":[{"id":"10.13039\/501100001711","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[2024,9,24]]},"abstract":"\n The heavy fermion (HF) state of\n \n \n d<\/mml:mi>\n <\/mml:math>\n <\/jats:inline-formula>\n -electron systems is of great current interest since it exhibits various exotic phases and phenomena that are reminiscent of the Kondo effect in\n \n \n f<\/mml:mi>\n <\/mml:math>\n <\/jats:inline-formula>\n -electron HF systems. Here, we present a combined infrared spectroscopy and first-principles band structure calculation study of the\n \n \n \n 3<\/mml:mn>\n d<\/mml:mi>\n <\/mml:mrow>\n <\/mml:math>\n <\/jats:inline-formula>\n -electron HF compound YFe\n \n \n \n \n 2<\/mml:mn>\n <\/mml:msub>\n <\/mml:math>\n <\/jats:inline-formula>\n Ge\n \n \n \n \n 2<\/mml:mn>\n <\/mml:msub>\n <\/mml:math>\n <\/jats:inline-formula>\n . The infrared response exhibits several charge-dynamical hallmarks of HF and a corresponding scaling behavior that resemble those of the\n \n \n f<\/mml:mi>\n <\/mml:math>\n <\/jats:inline-formula>\n -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 (\n \n \n \n \u0394<\/mml:mi>\n \u223c<\/mml:mo>\n <\/mml:mrow>\n <\/mml:math>\n <\/jats:inline-formula>\n 50 meV) and a strongly enhanced quasiparticle effective mass. Moreover, the temperature dependence of the infrared response indicates a crossover around\n \n \n \n \n T<\/mml:mi>\n \n \n \u2217<\/mml:mo>\n <\/mml:mrow>\n <\/mml:msup>\n \u223c<\/mml:mo>\n <\/mml:mrow>\n <\/mml:math>\n <\/jats:inline-formula>\n 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\n \n \n \n \n 2<\/mml:mn>\n <\/mml:msub>\n <\/mml:math>\n <\/jats:inline-formula>\n Ge\n \n \n \n \n 2<\/mml:mn>\n <\/mml:msub>\n <\/mml:math>\n <\/jats:inline-formula>\n is distinct from the Kondo scenario of the\n \n \n f<\/mml:mi>\n <\/mml:math>\n <\/jats:inline-formula>\n -electron HF compounds and even from that of the\n \n \n d<\/mml:mi>\n <\/mml:math>\n <\/jats:inline-formula>\n -electron iron-arsenide superconductor KFe\n \n \n \n \n 2<\/mml:mn>\n <\/mml:msub>\n <\/mml:math>\n <\/jats:inline-formula>\n As\n \n \n \n \n 2<\/mml:mn>\n <\/mml:msub>\n <\/mml:math>\n <\/jats:inline-formula>\n . For the latter, the HF state is driven by orbital-selective correlations due to a strong Hund\u2019s coupling. Instead, for YFe\n \n \n \n \n 2<\/mml:mn>\n <\/mml:msub>\n <\/mml:math>\n <\/jats:inline-formula>\n Ge\n \n \n \n \n 2<\/mml:mn>\n <\/mml:msub>\n <\/mml:math>\n <\/jats:inline-formula>\n 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\n \n \n \n 3<\/mml:mn>\n d<\/mml:mi>\n <\/mml:mrow>\n <\/mml:math>\n <\/jats:inline-formula>\n and Y\n \n \n \n 4<\/mml:mn>\n d<\/mml:mi>\n <\/mml:mrow>\n <\/mml:math>\n <\/jats:inline-formula>\n electrons, and electron correlations. This highlights that rather different mechanisms can be at the heart of the HF state in\n \n \n d<\/mml:mi>\n <\/mml:math>\n <\/jats:inline-formula>\n -electron systems.\n <\/jats:p>","DOI":"10.1073\/pnas.2401430121","type":"journal-article","created":{"date-parts":[[2024,9,19]],"date-time":"2024-09-19T13:37:38Z","timestamp":1726753058000},"update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":10,"title":["Unraveling the origin of Kondo-like behavior in the 3\n d<\/i>\n -electron heavy-fermion compound YFe\n 2<\/sub>\n Ge\n 2<\/sub>"],"prefix":"10.1073","volume":"121","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6449-0251","authenticated-orcid":false,"given":"Bing","family":"Xu","sequence":"first","affiliation":[{"name":"Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China"},{"name":"School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China"},{"name":"Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Fribourg CH-1700, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-1835-3002","authenticated-orcid":false,"given":"Rui","family":"Liu","sequence":"additional","affiliation":[{"name":"School of Physics and Astronomy and Center for Advanced Quantum Studies, Beijing Normal University, Beijing 100875, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0391-7899","authenticated-orcid":false,"given":"Hongliang","family":"Wo","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhiyu","family":"Liao","sequence":"additional","affiliation":[{"name":"Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China"},{"name":"School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shaohui","family":"Yi","sequence":"additional","affiliation":[{"name":"Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China"},{"name":"School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chunhong","family":"Li","sequence":"additional","affiliation":[{"name":"Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jun","family":"Zhao","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xianggang","family":"Qiu","sequence":"additional","affiliation":[{"name":"Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China"},{"name":"School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhiping","family":"Yin","sequence":"additional","affiliation":[{"name":"School of Physics and Astronomy and Center for Advanced Quantum Studies, Beijing Normal University, Beijing 100875, China"},{"name":"Key Laboratory of Multiscale Spin Physics (Ministry of Education), Beijing Normal University, Beijing 100875, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9957-3487","authenticated-orcid":false,"given":"Christian","family":"Bernhard","sequence":"additional","affiliation":[{"name":"Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Fribourg CH-1700, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[2024,9,19]]},"reference":[{"key":"e_1_3_4_1_2","doi-asserted-by":"publisher","DOI":"10.1103\/PhysRevLett.62.1927.5"},{"key":"e_1_3_4_2_2","doi-asserted-by":"publisher","DOI":"10.1126\/science.aaw3780"},{"key":"e_1_3_4_3_2","doi-asserted-by":"publisher","DOI":"10.1103\/RevModPhys.73.797"},{"key":"e_1_3_4_4_2","doi-asserted-by":"publisher","DOI":"10.1103\/PhysRevLett.130.226001"},{"key":"e_1_3_4_5_2","first-page":"021014","article-title":"Fractional chern insulator","volume":"1","author":"Regnault N.","year":"2011","unstructured":"N. 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