Bose-Einstein condensation superconductivity induced by disappearance of the nematic state

Takahiro Hashimoto; Yuichi Ota; Akihiro Tsuzuki; Tsubaki Nagashima; Akiko Fukushima; Shigeru Kasahara; Yuji Matsuda; Kohei Matsuura; Yuta Mizukami; Takasada Shibauchi; Shik Shin; Kozo Okazaki

doi:10.1126/SCIADV.ABB9052

Bose-Einstein condensation superconductivity induced by disappearance of the nematic state

Takahiro Hashimoto, Yuichi Ota, Akihiro Tsuzuki, Tsubaki Nagashima, Akiko Fukushima, Shigeru Kasahara, Yuji Matsuda, Kohei Matsuura, Yuta Mizukami, Takasada Shibauchi, Shik Shin, Kozo Okazaki

Research output: Contribution to journal › Article › peer-review

30 Citations (Scopus)

Abstract

The crossover from the superconductivity of the Bardeen-Cooper-Schrieffer (BCS) regime to the Bose-Einstein condensation (BEC) regime holds a key to understanding the nature of pairing and condensation of fermions. It has been mainly studied in ultracold atoms, but in solid systems, fundamentally previously unknown insights may be obtained because multiple energy bands and coexisting electronic orders strongly affect spin and orbital degrees of freedom. Here, we provide evidence for the BCS-BEC crossover in iron-based superconductors FeSe₁ − _xS_x from laser-excited angle-resolved photoemission spectroscopy. The system enters the BEC regime with x = 0.21, where the nematic state that breaks the orbital degeneracy is fully suppressed. The substitution dependence is opposite to the expectation for single-band superconductors, which calls for a new mechanism of BCS-BEC crossover in this system.

Original language	English
Article number	eabb9052
Journal	Science Advances
Volume	6
Issue number	45
DOIs	https://doi.org/10.1126/SCIADV.ABB9052
Publication status	Published - Nov 4 2020
Externally published	Yes

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10.1126/SCIADV.ABB9052

Cite this

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title = "Bose-Einstein condensation superconductivity induced by disappearance of the nematic state",

abstract = "The crossover from the superconductivity of the Bardeen-Cooper-Schrieffer (BCS) regime to the Bose-Einstein condensation (BEC) regime holds a key to understanding the nature of pairing and condensation of fermions. It has been mainly studied in ultracold atoms, but in solid systems, fundamentally previously unknown insights may be obtained because multiple energy bands and coexisting electronic orders strongly affect spin and orbital degrees of freedom. Here, we provide evidence for the BCS-BEC crossover in iron-based superconductors FeSe1 − xSx from laser-excited angle-resolved photoemission spectroscopy. The system enters the BEC regime with x = 0.21, where the nematic state that breaks the orbital degeneracy is fully suppressed. The substitution dependence is opposite to the expectation for single-band superconductors, which calls for a new mechanism of BCS-BEC crossover in this system.",

author = "Takahiro Hashimoto and Yuichi Ota and Akihiro Tsuzuki and Tsubaki Nagashima and Akiko Fukushima and Shigeru Kasahara and Yuji Matsuda and Kohei Matsuura and Yuta Mizukami and Takasada Shibauchi and Shik Shin and Kozo Okazaki",

note = "Funding Information: This research is supported by Grants-in-Aid for Scientific Research (KAKENHI) (grant numbers JP19H00651, JP19H01818, JP18H05227, JP19H00649, JP18H01177, JP18K13492, and JP20H02600) and Grants-in-Aid on Innovative Areas ?Quantum Liquid Crystals? (grant numbers JP19H05824 and JP19H05826) and ?Topological Material Science? (grant number JP15H05852) from the Japan Society for the Promotion of Science (JSPS). T.H. acknowledges the JSPS Research Fellowship for Young Scientists (DC2). Publisher Copyright: Copyright {\textcopyright} 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).",

year = "2020",

month = nov,

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doi = "10.1126/SCIADV.ABB9052",

language = "English",

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T1 - Bose-Einstein condensation superconductivity induced by disappearance of the nematic state

AU - Hashimoto, Takahiro

AU - Ota, Yuichi

AU - Tsuzuki, Akihiro

AU - Nagashima, Tsubaki

AU - Fukushima, Akiko

AU - Kasahara, Shigeru

AU - Matsuda, Yuji

AU - Matsuura, Kohei

AU - Mizukami, Yuta

AU - Shibauchi, Takasada

AU - Shin, Shik

AU - Okazaki, Kozo

N1 - Funding Information: This research is supported by Grants-in-Aid for Scientific Research (KAKENHI) (grant numbers JP19H00651, JP19H01818, JP18H05227, JP19H00649, JP18H01177, JP18K13492, and JP20H02600) and Grants-in-Aid on Innovative Areas ?Quantum Liquid Crystals? (grant numbers JP19H05824 and JP19H05826) and ?Topological Material Science? (grant number JP15H05852) from the Japan Society for the Promotion of Science (JSPS). T.H. acknowledges the JSPS Research Fellowship for Young Scientists (DC2). Publisher Copyright: Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).

PY - 2020/11/4

Y1 - 2020/11/4

N2 - The crossover from the superconductivity of the Bardeen-Cooper-Schrieffer (BCS) regime to the Bose-Einstein condensation (BEC) regime holds a key to understanding the nature of pairing and condensation of fermions. It has been mainly studied in ultracold atoms, but in solid systems, fundamentally previously unknown insights may be obtained because multiple energy bands and coexisting electronic orders strongly affect spin and orbital degrees of freedom. Here, we provide evidence for the BCS-BEC crossover in iron-based superconductors FeSe1 − xSx from laser-excited angle-resolved photoemission spectroscopy. The system enters the BEC regime with x = 0.21, where the nematic state that breaks the orbital degeneracy is fully suppressed. The substitution dependence is opposite to the expectation for single-band superconductors, which calls for a new mechanism of BCS-BEC crossover in this system.

AB - The crossover from the superconductivity of the Bardeen-Cooper-Schrieffer (BCS) regime to the Bose-Einstein condensation (BEC) regime holds a key to understanding the nature of pairing and condensation of fermions. It has been mainly studied in ultracold atoms, but in solid systems, fundamentally previously unknown insights may be obtained because multiple energy bands and coexisting electronic orders strongly affect spin and orbital degrees of freedom. Here, we provide evidence for the BCS-BEC crossover in iron-based superconductors FeSe1 − xSx from laser-excited angle-resolved photoemission spectroscopy. The system enters the BEC regime with x = 0.21, where the nematic state that breaks the orbital degeneracy is fully suppressed. The substitution dependence is opposite to the expectation for single-band superconductors, which calls for a new mechanism of BCS-BEC crossover in this system.

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Bose-Einstein condensation superconductivity induced by disappearance of the nematic state

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