@article{512ed2bf3212401990c6a3eaf8ef5b61,
title = "Quantum valence criticality in a correlated metal",
abstract = "A valence critical end point existing near the absolute zero provides a unique case for the study of a quantum version of the strong density fluctuation at the Widom line in the supercritical fluids. Although singular charge and orbital dynamics are suggested theoretically to alter the electronic structure significantly, breaking down the standard quasi-particle picture, this has never been confirmed experimentally to date. We provide the first empirical evidence that the proximity to quantum valence criticality leads to a clear breakdown of Fermi liquid behavior. Our detailed study of the mixed valence compound a-YbAlB4 reveals that a small chemical substitution induces a sharp valence crossover, accompanied by a pronounced non-Fermi liquid behavior characterized by a divergent effective mass and unusual T/B scaling in the magnetization.",
author = "Kentaro Kuga and Yosuke Matsumoto and Mario Okawa and Shintaro Suzuki and Takahiro Tomita and Keita Sone and Yasuyuki Shimura and Toshiro Sakakibara and Daisuke Nishio-Hamane and Yoshitomo Karaki and Yasutaka Takata and Masaharu Matsunami and Ritsuko Eguchi and Munetaka Taguchi and Ashish Chainani and Shik Shin and Kenji Tamasaku and Yoshinori Nishino and Makina Yabashi and Tetsuya Ishikawa and Satoru Nakatsuji",
note = "Funding Information: We thank E. C. T. O'Farrell, N. Horie, S. Watanabe, and K. Ueda for support and useful discussions. Funding: This work was partially supported by Grants-in-Aid for Scientific Research (16H02209) and Program for Advancing Strategic International Networks to Accelerate the Circulation of Talented Researchers (no. R2604) from the Japanese Society for the Promotion of Science; by Grants-in-Aids for Scientific Research on Innovative Areas (15H05882, 15H05883, and 26103002) of the Ministry of Education, Culture, Sports, Science, and Technology of Japan; and by the Core Research for Evolutionary Science and Technology (JPMJCR15Q5), Japan Science and Technology Agency. The use of the facilities of the Materials Design and Characterization Laboratory at the Institute for Solid State Physics, The University of Tokyo, is acknowledged. HAXPES experiments were performed at BL29XU in SPring-8 with the approval of RIKEN (proposal nos. 20090041 and 20100057). Author contributions: K.K. and Y.M. contributed equally to this project including sample preparation, thermodynamic and transport measurements, and data analysis/interpretation. M.O. conducted HAXPES measurements and contributed to data analysis and interpretation. Y.T., M.M., R.E., M.T., A.C., S. Shin, K.T., Y.N., M.Y., and T.I. contributed to HAXPES measurements. S. Suzuki., K.S., and D.N.-H. contributed to structural analyses. Y.S., T.S., and Y.K. carried out low-temperature magnetization measurements. S.N. conceived the project and planed the research and contributed to crystal growth, characterization, and data interpretation. S.N., Y.M., and K.K. wrote the paper. All authors discussed the results and commented on the manuscript. Competing interests: The authors declare that they have no competing interests. Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Additional data related to this paper may be requested from the authors. Publisher Copyright: Copyright {\textcopyright} 2018 The Authors.",
year = "2018",
month = feb,
day = "23",
doi = "10.1126/sciadv.aao3547",
language = "English",
volume = "4",
journal = "Science advances",
issn = "2375-2548",
publisher = "American Association for the Advancement of Science",
number = "2",
}