Charge-transfer properties and electron dynamics in ferromagnetic CoS2
(2025) In Physical Review B 112(16).- Abstract
We investigated the element-specific electronic structure and charge-carrier dynamics of a single-crystal ferromagnet CoS2 with complementary x-ray spectroscopy techniques. Hard x-ray photoemission (HAXPES) is used to provide crucial information on the bulk electronic structure and chemical bonding in CoS2 that is compared against the isoelectronic paramagnet CoSe2. The Co 1s core-level line shows several satellite features for CoS2, showing explicit charge-transfer processes and local screening of the core hole by S ligands, whereas no such features are observed in CoSe2. The satellite structures indicate the electronic configuration of divalent Co2+ as a combination of... (More)
We investigated the element-specific electronic structure and charge-carrier dynamics of a single-crystal ferromagnet CoS2 with complementary x-ray spectroscopy techniques. Hard x-ray photoemission (HAXPES) is used to provide crucial information on the bulk electronic structure and chemical bonding in CoS2 that is compared against the isoelectronic paramagnet CoSe2. The Co 1s core-level line shows several satellite features for CoS2, showing explicit charge-transfer processes and local screening of the core hole by S ligands, whereas no such features are observed in CoSe2. The satellite structures indicate the electronic configuration of divalent Co2+ as a combination of d8L and d9L2 in addition to the nominal ionic d7 state, where L¯ represents an S 3phole. We employ resonant Auger ¯spectroscopy ¯ across the S K-edge for CoS2 to obtain electron delocalization times to adjacent Co atomic sites. The fast carrier dynamics are attributed to strongly screened Coulomb interactions and hence a facile carrier delocalization. The strong hybridization formed between the Co 3d and S 3p states with pronounced charge-transfer character reflects a self-doped system with a finite density n of holes at the sulfur site (L¯ n), in line with recent models that indicate a negative charge-transfer energy for CoS2. In addition to HAXPES data, we also report on experimental and theoretical L-edge x-ray absorption and x-ray magnetic circular dichroism data for CoS2 that demonstrate multiconfiguration effects in the excitation process. To enable a direct comparison of the experimental spectra, we used density functional theory calculations to obtain the projected density of states to describe the ground-state electronic structure. The existence of fast carrier dynamics and strong charge-transfer properties, demonstrated in this study, highlights the unique nature of CoS2 with a wide potential in topological spintronics applications and integration in energy-related device platforms.
(Less)
- author
- organization
- publishing date
- 2025-10
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Physical Review B
- volume
- 112
- issue
- 16
- article number
- 165115
- publisher
- American Physical Society
- external identifiers
-
- scopus:105020662149
- ISSN
- 2469-9950
- DOI
- 10.1103/vg4c-h785
- language
- English
- LU publication?
- yes
- id
- b3930a22-1dc5-44e9-a0ea-9f9540b1b944
- date added to LUP
- 2025-12-16 14:31:12
- date last changed
- 2025-12-16 14:32:14
@article{b3930a22-1dc5-44e9-a0ea-9f9540b1b944,
abstract = {{<p>We investigated the element-specific electronic structure and charge-carrier dynamics of a single-crystal ferromagnet CoS<sub>2</sub> with complementary x-ray spectroscopy techniques. Hard x-ray photoemission (HAXPES) is used to provide crucial information on the bulk electronic structure and chemical bonding in CoS<sub>2</sub> that is compared against the isoelectronic paramagnet CoSe<sub>2</sub>. The Co 1s core-level line shows several satellite features for CoS<sub>2</sub>, showing explicit charge-transfer processes and local screening of the core hole by S ligands, whereas no such features are observed in CoSe<sub>2</sub>. The satellite structures indicate the electronic configuration of divalent Co<sup>2+</sup> as a combination of d<sup>8</sup>L and d<sup>9</sup>L<sup>2</sup> in addition to the nominal ionic d<sup>7</sup> state, where L<sub>¯</sub> represents an S 3phole. We employ resonant Auger <sup>¯</sup>spectroscopy <sup>¯</sup> across the S K-edge for CoS<sub>2</sub> to obtain electron delocalization times to adjacent Co atomic sites. The fast carrier dynamics are attributed to strongly screened Coulomb interactions and hence a facile carrier delocalization. The strong hybridization formed between the Co 3d and S 3p states with pronounced charge-transfer character reflects a self-doped system with a finite density n of holes at the sulfur site (L<sub>¯</sub> <sup>n</sup>), in line with recent models that indicate a negative charge-transfer energy for CoS<sub>2</sub>. In addition to HAXPES data, we also report on experimental and theoretical L-edge x-ray absorption and x-ray magnetic circular dichroism data for CoS<sub>2</sub> that demonstrate multiconfiguration effects in the excitation process. To enable a direct comparison of the experimental spectra, we used density functional theory calculations to obtain the projected density of states to describe the ground-state electronic structure. The existence of fast carrier dynamics and strong charge-transfer properties, demonstrated in this study, highlights the unique nature of CoS<sub>2</sub> with a wide potential in topological spintronics applications and integration in energy-related device platforms.</p>}},
author = {{Abdel-Hafiez, Mahmoud and Johansson, Fredrik O.L. and Chakraborty, Anwesha and Pavelka, Martin and Ghosh, Anirudha and Chareev, D. A. and Vasiliev, A. N. and Edström, Alexander and Delin, Anna and Eriksson, Olle and Karmakar, Debjani and Phuyal, Dibya}},
issn = {{2469-9950}},
language = {{eng}},
number = {{16}},
publisher = {{American Physical Society}},
series = {{Physical Review B}},
title = {{Charge-transfer properties and electron dynamics in ferromagnetic CoS<sub>2</sub>}},
url = {{http://dx.doi.org/10.1103/vg4c-h785}},
doi = {{10.1103/vg4c-h785}},
volume = {{112}},
year = {{2025}},
}