Extended nematic quantum criticality in FeSe<sub>x</sub>Te<sub>1-x</sub>

ORAL

Abstract

Unconventional superconductivity is often accompanied by non-Fermi liquid behavior, which arises near a quantum critical point — a point where an electronic ordered phase is terminated at absolute zero by non-thermal parameters [1]. Quantum criticality may extend over a wide region of parameter space, yet the materials exhibiting such behavior are limited [2]. Here, we report evidence for extended quantum criticality in strongly correlated iron-based superconductors FeSexTe1−x, characterized by temperature-linear resistivity and logarithmic divergence of thermoelectricity over a wide substitution range of 0.08 ≤ x ≤ 0.45 situated between antiferromagnetic and nematic quantum critical points. Notably, the Seebeck coefficient peaks sharply at the nematic quantum critical point x = 0.45, suggesting a dominant role of nematic fluctuations in the NFL transport. Our results reveal the pervasive nature of the extended quantum criticality and could open new avenues for exploring novel superconducting phases arising from strong quantum fluctuations.

*This work was supported by JSPS KAKENHI Grants (No. 22K13988, No. 24K17020, No. 22K18965, No. 23H04017, No. 23H05431, No. 23H05462, and No. 23H04862), JST FOREST (Grant No. JPMJFR2038), JST CREST (Grant No. JPMJCR1874 and No. JPMJCR23O3), Mitsubishi Foundation, the special fund of Institute of Industrial Science, The University of Tokyo, and the RIKEN TRIP initiative (Many-body Electron Systems).

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Presenters

  • Yuki Sato

    • RIKEN

Authors

  • Yuki Sato

    • RIKEN

  • Soma Nagahama

    • University of Tokyo

  • Ilya Belopolski

    • RIKEN

  • Ryutaro Yoshimi

    • Department of Advanced Materials Science, The University of Tokyo

  • Minoru Kawamura

    • RIKEN Center for Emergent Matter Science (CEMS)

  • Atsushi Tsukazaki

    • Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), The University of Tokyo
    • Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo

  • Akiyoshi Yamada

    • ISSP, University of Tokyo

  • Masashi Tokunaga

    • ISSP, University of Tokyo
    • Univ of Tokyo

  • Naoya Kanazawa

    • Institute of Industrial Science, University of Tokyo

  • Kei S Takahashi

    • RIKEN

  • Yoshichika Onuki

    • RIKEN

  • Masashi Kawasaki

    • RIKEN Center for Emergent Matter Science (CEMS), Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), The University of Tokyo
    • RIKEN Center for Emergent Matter Science (CEMS), Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo

  • Yoshinori Tokura

    • RIKEN Center for Emergent Matter Science (CEMS), Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), The University of Tokyo
    • Univ of Tokyo
    • The University of Tokyo, RIKEN Center for Emergent Matter Science (CEMS), Tokyo college, The University of Tokyo
    • RIKEN Center for Emergent Matter Science (CEMS); Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), Univ. of Tokyo; Tokyo College, Univ. of Tokyo
    • RIKEN Center for Emergent Matter Science (CEMS), Department of Applied Physics, Quantum-Phase Electronics Center (QPEC) and Tokyo College, University of Tokyo