Uncovering Exotic Topological Quantum States in Pure and Magnetically-Doped Pyrite OsS2
(2026) In Advanced Quantum Technologies- Abstract
Discovering topological quantum materials that combine nontrivial topology with large bandgaps and experimentally accessible signatures remains a central pursuit in condensed matter physics. We demonstrate, through first-principles calculations and tight-binding modeling, that pyrite-type osmium disulfide (OsS2) is a fragile topological insulator (FTI) characterized by an exceptionally large direct bandgap of 602 meV, placing it among the highest-gap FTIs reported. Contrary to typical fragile phases that lack prominent boundary states, OsS2 features distinct, symmetry-protected gapless surface states across multiple cleavage planes, enabling direct experimental verification via angle-resolved photoemission... (More)
Discovering topological quantum materials that combine nontrivial topology with large bandgaps and experimentally accessible signatures remains a central pursuit in condensed matter physics. We demonstrate, through first-principles calculations and tight-binding modeling, that pyrite-type osmium disulfide (OsS2) is a fragile topological insulator (FTI) characterized by an exceptionally large direct bandgap of 602 meV, placing it among the highest-gap FTIs reported. Contrary to typical fragile phases that lack prominent boundary states, OsS2 features distinct, symmetry-protected gapless surface states across multiple cleavage planes, enabling direct experimental verification via angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM). Additionally, the presence of van Hove singularities in the electronic structure further distinguishes OsS2 as a unique 3D quantum material. By systematically varying the magnetic moment from 0 to 4 µB through substitutional doping with Pd, Fe, Ni, and Co, we map out a rich topological phase diagram. This diagram reveals transitions from the FTI phase to a strong topological insulator (STI), a topological semimetal, a three-dimensional quantum anomalous Hall (3D-QAH) insulator, and ultimately a trivial magnetic semiconductor, each phase corresponding to a specific magnetic moment. The structural similarity and near-identical lattice constants of PdS2, FeS2, NiS2, and CoS2 with OsS2, all of which crystallize in the cubic pyrite phase, suggest the practical realization of these phases. Collectively, our findings establish OsS2 as a promising platform for exploring fragile topology, tunable quantum phase transitions, and novel boundary phenomena within a single material system.
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- author
- Sufyan, Ali LU ; Abdullah, Hasan M. ; Johansson, Gustav ; Tyner, Alexander C. ; Qayyum, Hafiz Adil ; Gilani, Ghulam Abbas ; Villaos, Rovi Angelo B. ; Huang, Zhi Quan ; Chuang, Feng Chuan and Larsson, J. Andreas
- organization
- publishing date
- 2026
- type
- Contribution to journal
- publication status
- epub
- subject
- keywords
- 3D quantum anomalous Hall insulators, first-principles calculations, fragile insulators, tight-binding model, van Hove singularities
- in
- Advanced Quantum Technologies
- publisher
- Wiley
- external identifiers
-
- scopus:105028131693
- ISSN
- 2511-9044
- DOI
- 10.1002/qute.202500749
- language
- English
- LU publication?
- yes
- id
- d6f64523-7971-47ad-b023-d87251ce0644
- date added to LUP
- 2026-02-25 12:34:59
- date last changed
- 2026-02-25 12:36:24
@article{d6f64523-7971-47ad-b023-d87251ce0644,
abstract = {{<p>Discovering topological quantum materials that combine nontrivial topology with large bandgaps and experimentally accessible signatures remains a central pursuit in condensed matter physics. We demonstrate, through first-principles calculations and tight-binding modeling, that pyrite-type osmium disulfide (OsS<sub>2</sub>) is a fragile topological insulator (FTI) characterized by an exceptionally large direct bandgap of 602 meV, placing it among the highest-gap FTIs reported. Contrary to typical fragile phases that lack prominent boundary states, OsS<sub>2</sub> features distinct, symmetry-protected gapless surface states across multiple cleavage planes, enabling direct experimental verification via angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM). Additionally, the presence of van Hove singularities in the electronic structure further distinguishes OsS<sub>2</sub> as a unique 3D quantum material. By systematically varying the magnetic moment from 0 to 4 µB through substitutional doping with Pd, Fe, Ni, and Co, we map out a rich topological phase diagram. This diagram reveals transitions from the FTI phase to a strong topological insulator (STI), a topological semimetal, a three-dimensional quantum anomalous Hall (3D-QAH) insulator, and ultimately a trivial magnetic semiconductor, each phase corresponding to a specific magnetic moment. The structural similarity and near-identical lattice constants of PdS<sub>2</sub>, FeS<sub>2</sub>, NiS<sub>2</sub>, and CoS<sub>2</sub> with OsS<sub>2</sub>, all of which crystallize in the cubic pyrite phase, suggest the practical realization of these phases. Collectively, our findings establish OsS<sub>2</sub> as a promising platform for exploring fragile topology, tunable quantum phase transitions, and novel boundary phenomena within a single material system.</p>}},
author = {{Sufyan, Ali and Abdullah, Hasan M. and Johansson, Gustav and Tyner, Alexander C. and Qayyum, Hafiz Adil and Gilani, Ghulam Abbas and Villaos, Rovi Angelo B. and Huang, Zhi Quan and Chuang, Feng Chuan and Larsson, J. Andreas}},
issn = {{2511-9044}},
keywords = {{3D quantum anomalous Hall insulators; first-principles calculations; fragile insulators; tight-binding model; van Hove singularities}},
language = {{eng}},
publisher = {{Wiley}},
series = {{Advanced Quantum Technologies}},
title = {{Uncovering Exotic Topological Quantum States in Pure and Magnetically-Doped Pyrite OsS<sub>2</sub>}},
url = {{http://dx.doi.org/10.1002/qute.202500749}},
doi = {{10.1002/qute.202500749}},
year = {{2026}},
}