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Main Authors: Nitzav, Yuval, Dishi, Abigail, Lohani, Himanshu, Sidilkover, Ittai, Ophir, Noam, Gofman, Roni Anna, Almoalem, Avior, Mangel, Ilay, Ragoler, Nitzan, Bertran, Francois, Sánchez-Barriga, Jaime, Marchenko, Dmitry, Varykhalov, Andrei, Plumb, Nicholas Clark, Feldman, Irena, Soifer, Hadas, Keselman, Anna, Kanigel, Amit
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2511.23084
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author Nitzav, Yuval
Dishi, Abigail
Lohani, Himanshu
Sidilkover, Ittai
Ophir, Noam
Gofman, Roni Anna
Almoalem, Avior
Mangel, Ilay
Ragoler, Nitzan
Bertran, Francois
Sánchez-Barriga, Jaime
Marchenko, Dmitry
Varykhalov, Andrei
Plumb, Nicholas Clark
Feldman, Irena
Soifer, Hadas
Keselman, Anna
Kanigel, Amit
author_facet Nitzav, Yuval
Dishi, Abigail
Lohani, Himanshu
Sidilkover, Ittai
Ophir, Noam
Gofman, Roni Anna
Almoalem, Avior
Mangel, Ilay
Ragoler, Nitzan
Bertran, Francois
Sánchez-Barriga, Jaime
Marchenko, Dmitry
Varykhalov, Andrei
Plumb, Nicholas Clark
Feldman, Irena
Soifer, Hadas
Keselman, Anna
Kanigel, Amit
contents Trions, three-body bound states composed of an exciton and an additional charge, are typically fragile and require external excitation to form. Here, we report the spontaneous emergence of a stable trion gas at the surface of the layered semiconductor Ta2NiS5, revealed through angle-resolved photoemission spectroscopy. We observe a sharp, highly localized in-gap feature that cannot be explained by conventional band-theory. Instead, we argue that it arises from the formation of negative trions, stabilized by surface-induced band bending and the material's quasi-one-dimensional geometry. Unlike excitons, these trions form without optical pumping and persist at equilibrium, marking a rare example of an interaction-driven surface state in a nominally conventional semiconductor. Our findings establish Ta2NiS5 as a unique platform for exploring many-body physics at surfaces and open new avenues for studying and controlling collective excitations in low-dimensional systems.
format Preprint
id arxiv_https___arxiv_org_abs_2511_23084
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Trion gas on the surface of a failed excitonic insulator
Nitzav, Yuval
Dishi, Abigail
Lohani, Himanshu
Sidilkover, Ittai
Ophir, Noam
Gofman, Roni Anna
Almoalem, Avior
Mangel, Ilay
Ragoler, Nitzan
Bertran, Francois
Sánchez-Barriga, Jaime
Marchenko, Dmitry
Varykhalov, Andrei
Plumb, Nicholas Clark
Feldman, Irena
Soifer, Hadas
Keselman, Anna
Kanigel, Amit
Strongly Correlated Electrons
Materials Science
Trions, three-body bound states composed of an exciton and an additional charge, are typically fragile and require external excitation to form. Here, we report the spontaneous emergence of a stable trion gas at the surface of the layered semiconductor Ta2NiS5, revealed through angle-resolved photoemission spectroscopy. We observe a sharp, highly localized in-gap feature that cannot be explained by conventional band-theory. Instead, we argue that it arises from the formation of negative trions, stabilized by surface-induced band bending and the material's quasi-one-dimensional geometry. Unlike excitons, these trions form without optical pumping and persist at equilibrium, marking a rare example of an interaction-driven surface state in a nominally conventional semiconductor. Our findings establish Ta2NiS5 as a unique platform for exploring many-body physics at surfaces and open new avenues for studying and controlling collective excitations in low-dimensional systems.
title Trion gas on the surface of a failed excitonic insulator
topic Strongly Correlated Electrons
Materials Science
url https://arxiv.org/abs/2511.23084