Topology meets time-reversal symmetry breaking in FeSe1−xTex superconductors

Masaki Roppongi; Yipeng Cai; Koki Ogawa; Supeng Liu; Guoqiang Zhao; Mohamed Oudah; Takenori Fujii; Kumpei Imamura; Shengjie Fang; Kota Ishihara; Kenichiro Hashimoto; Kohei Matsuura; Yuta Mizukami; Mathew Pula; Cyrus Young; Igor Marković; Douglas A. Bonn; Takao Watanabe; Aichi Yamashita; Yoshikazu Mizuguchi; Graeme M. Luke; Kenji M. Kojima; Yasutomo J. Uemura; Tasakada Shibauchi

doi:10.1038/s41467-025-61651-y

Topology meets time-reversal symmetry breaking in FeSe_1−xTe_x superconductors

Masaki Roppongi^*
, Yipeng Cai
, Koki Ogawa
, Supeng Liu
, Guoqiang Zhao
, Mohamed Oudah
, Takenori Fujii
, Kumpei Imamura
, Shengjie Fang
, Kota Ishihara
, Kenichiro Hashimoto
, Kohei Matsuura
, Yuta Mizukami
, Mathew Pula
, Cyrus Young
, Igor Marković
, Douglas A. Bonn
, Takao Watanabe
, Aichi Yamashita
, Yoshikazu Mizuguchi

Graeme M. Luke, Kenji M. Kojima, Yasutomo J. Uemura^*, Tasakada Shibauchi^*

^*Corresponding author for this work

Physics and Astronomy

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

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Abstract

Time-reversal symmetry breaking (TRSB) in magnetic topological insulators induces a Dirac gap in the topological surface state (TSS), leading to exotic phenomena such as the quantum anomalous Hall effect. Yet, the interplay between TRSB and topology in superconductors remains underexplored due to limited suitable materials. Here we employ zero-field muon spin relaxation (μSR) as a sensitive probe of TRSB to map out the electronic phase diagrams of iron-chalcogenide superconductors FeSe_1−xTe_x. For the Te composition x = 0.64 with the highest superconducting transition temperature T_c = 14.5 K, which is known to host a TSS and Majorana zero modes within vortices, we detect spontaneous magnetic fields below T_c distinct from a magnetic order. This signifies a TRSB superconducting state in the bulk, revealing the convergence of unconventional TRSB superconductivity with topologically nontrivial electronic structures in FeSe_1−xTe_x. Given the relatively high T_c and the tunability of the Fermi level through chemical substitution, iron-chalcogenide superconductors offer an intriguing platform for investigating the synergy between topological superconductivity and TRSB.

Original language	English
Article number	6573
Number of pages	8
Journal	Nature Communications
Volume	16
DOIs	https://doi.org/10.1038/s41467-025-61651-y
Publication status	Published - 23 Jul 2025

ASJC Scopus subject areas

General Chemistry
General Biochemistry,Genetics and Molecular Biology
General Physics and Astronomy

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Cite this

Roppongi, M., Cai, Y., Ogawa, K., Liu, S., Zhao, G., Oudah, M., Fujii, T., Imamura, K., Fang, S., Ishihara, K., Hashimoto, K., Matsuura, K., Mizukami, Y., Pula, M., Young, C., Marković, I., Bonn, D. A., Watanabe, T., Yamashita, A., ... Shibauchi, T. (2025). Topology meets time-reversal symmetry breaking in FeSe_1−xTe_x superconductors. Nature Communications, 16, Article 6573. https://doi.org/10.1038/s41467-025-61651-y

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title = "Topology meets time-reversal symmetry breaking in FeSe1−xTex superconductors",

abstract = "Time-reversal symmetry breaking (TRSB) in magnetic topological insulators induces a Dirac gap in the topological surface state (TSS), leading to exotic phenomena such as the quantum anomalous Hall effect. Yet, the interplay between TRSB and topology in superconductors remains underexplored due to limited suitable materials. Here we employ zero-field muon spin relaxation (μSR) as a sensitive probe of TRSB to map out the electronic phase diagrams of iron-chalcogenide superconductors FeSe1−xTex. For the Te composition x = 0.64 with the highest superconducting transition temperature Tc = 14.5 K, which is known to host a TSS and Majorana zero modes within vortices, we detect spontaneous magnetic fields below Tc distinct from a magnetic order. This signifies a TRSB superconducting state in the bulk, revealing the convergence of unconventional TRSB superconductivity with topologically nontrivial electronic structures in FeSe1−xTex. Given the relatively high Tc and the tunability of the Fermi level through chemical substitution, iron-chalcogenide superconductors offer an intriguing platform for investigating the synergy between topological superconductivity and TRSB.",

author = "Masaki Roppongi and Yipeng Cai and Koki Ogawa and Supeng Liu and Guoqiang Zhao and Mohamed Oudah and Takenori Fujii and Kumpei Imamura and Shengjie Fang and Kota Ishihara and Kenichiro Hashimoto and Kohei Matsuura and Yuta Mizukami and Mathew Pula and Cyrus Young and Igor Markovi{\'c} and Bonn, \{Douglas A.\} and Takao Watanabe and Aichi Yamashita and Yoshikazu Mizuguchi and Luke, \{Graeme M.\} and Kojima, \{Kenji M.\} and Uemura, \{Yasutomo J.\} and Tasakada Shibauchi",

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Roppongi, M, Cai, Y, Ogawa, K, Liu, S, Zhao, G, Oudah, M, Fujii, T, Imamura, K, Fang, S, Ishihara, K, Hashimoto, K, Matsuura, K, Mizukami, Y, Pula, M, Young, C, Marković, I, Bonn, DA, Watanabe, T, Yamashita, A, Mizuguchi, Y, Luke, GM, Kojima, KM, Uemura, YJ & Shibauchi, T 2025, 'Topology meets time-reversal symmetry breaking in FeSe_1−xTe_x superconductors', Nature Communications, vol. 16, 6573. https://doi.org/10.1038/s41467-025-61651-y

TY - JOUR

T1 - Topology meets time-reversal symmetry breaking in FeSe1−xTex superconductors

AU - Roppongi, Masaki

AU - Cai, Yipeng

AU - Ogawa, Koki

AU - Liu, Supeng

AU - Zhao, Guoqiang

AU - Oudah, Mohamed

AU - Fujii, Takenori

AU - Imamura, Kumpei

AU - Fang, Shengjie

AU - Ishihara, Kota

AU - Hashimoto, Kenichiro

AU - Matsuura, Kohei

AU - Mizukami, Yuta

AU - Pula, Mathew

AU - Young, Cyrus

AU - Marković, Igor

AU - Bonn, Douglas A.

AU - Watanabe, Takao

AU - Yamashita, Aichi

AU - Mizuguchi, Yoshikazu

AU - Luke, Graeme M.

AU - Kojima, Kenji M.

AU - Uemura, Yasutomo J.

AU - Shibauchi, Tasakada

PY - 2025/7/23

Y1 - 2025/7/23

N2 - Time-reversal symmetry breaking (TRSB) in magnetic topological insulators induces a Dirac gap in the topological surface state (TSS), leading to exotic phenomena such as the quantum anomalous Hall effect. Yet, the interplay between TRSB and topology in superconductors remains underexplored due to limited suitable materials. Here we employ zero-field muon spin relaxation (μSR) as a sensitive probe of TRSB to map out the electronic phase diagrams of iron-chalcogenide superconductors FeSe1−xTex. For the Te composition x = 0.64 with the highest superconducting transition temperature Tc = 14.5 K, which is known to host a TSS and Majorana zero modes within vortices, we detect spontaneous magnetic fields below Tc distinct from a magnetic order. This signifies a TRSB superconducting state in the bulk, revealing the convergence of unconventional TRSB superconductivity with topologically nontrivial electronic structures in FeSe1−xTex. Given the relatively high Tc and the tunability of the Fermi level through chemical substitution, iron-chalcogenide superconductors offer an intriguing platform for investigating the synergy between topological superconductivity and TRSB.

AB - Time-reversal symmetry breaking (TRSB) in magnetic topological insulators induces a Dirac gap in the topological surface state (TSS), leading to exotic phenomena such as the quantum anomalous Hall effect. Yet, the interplay between TRSB and topology in superconductors remains underexplored due to limited suitable materials. Here we employ zero-field muon spin relaxation (μSR) as a sensitive probe of TRSB to map out the electronic phase diagrams of iron-chalcogenide superconductors FeSe1−xTex. For the Te composition x = 0.64 with the highest superconducting transition temperature Tc = 14.5 K, which is known to host a TSS and Majorana zero modes within vortices, we detect spontaneous magnetic fields below Tc distinct from a magnetic order. This signifies a TRSB superconducting state in the bulk, revealing the convergence of unconventional TRSB superconductivity with topologically nontrivial electronic structures in FeSe1−xTex. Given the relatively high Tc and the tunability of the Fermi level through chemical substitution, iron-chalcogenide superconductors offer an intriguing platform for investigating the synergy between topological superconductivity and TRSB.

U2 - 10.1038/s41467-025-61651-y

DO - 10.1038/s41467-025-61651-y

M3 - Article

AN - SCOPUS:105011365824

SN - 2041-1723

VL - 16

JO - Nature Communications

JF - Nature Communications

M1 - 6573

ER -