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Unusual mixed spin-state of Co3+ in the ground state of LaSrCoO4: Combined high-pressure and high-temperature study

Haw, Shu Chih ; Hu, Zhiwei ; Lin, Hong Ji ; Lee, Jenn Min LU ; Ishii, Hirofumi ; Hiraoka, Nozomu ; Meléndez-sans, Anna ; Komarek, Alexander C. ; Tjeng, Liu Hao and Chen, Kai , et al. (2020) In Journal of Alloys and Compounds
Abstract
The nature of the non-magnetic to paramagnetic transition of Co3+ oxide LaCoO3 was strongly disputed in the literature for many decades from a low-spin (LS) state below 20 K and to a mixed LS state and high-spin (HS) state or an intermediate-spin (IS) state above 100 K. In this context, the layered perovskite LaSrCoO4 is more favorable for a Jahn-Teller-active IS state because of an elongated distortion, but has been scarcely studied with experimental X-ray spectroscopies as a function of temperature or external pressure. Here, our Co-L2,3 X-ray absorption spectroscopic study indicates a mixture of 40% HS-Co3+ and 60% LS-Co3+ for LaSrCoO4 against 25% HS-Co3+ and 75% LS-Co3+ for LaCoO3 at 300 K and ambient pressure (AP). At 10 K, we... (More)
The nature of the non-magnetic to paramagnetic transition of Co3+ oxide LaCoO3 was strongly disputed in the literature for many decades from a low-spin (LS) state below 20 K and to a mixed LS state and high-spin (HS) state or an intermediate-spin (IS) state above 100 K. In this context, the layered perovskite LaSrCoO4 is more favorable for a Jahn-Teller-active IS state because of an elongated distortion, but has been scarcely studied with experimental X-ray spectroscopies as a function of temperature or external pressure. Here, our Co-L2,3 X-ray absorption spectroscopic study indicates a mixture of 40% HS-Co3+ and 60% LS-Co3+ for LaSrCoO4 against 25% HS-Co3+ and 75% LS-Co3+ for LaCoO3 at 300 K and ambient pressure (AP). At 10 K, we observed a sizable magnetic-circular-dichroism signal and a clear HS state of the magnetic Co3+ ion from the Co-L2,3 edge of LaSrCoO4. This result demonstrates that the HS state is already populated in the ground state versus a pure LS ground state in LaCoO3. A quantitative change of quantum number of the spin of the Co3+ ion of LaSrCoO4 as a function of pressure and temperature investigated systematically with Co-Kβ X-ray emission experiments firmly demonstrates not only a mixed state of LS/HS at 300 K and AP but also a presence of the pure LS-Co3+ and HS-Co3+ states only under high pressure and high temperature, respectively. (Less)
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Alloys and Compounds
article number
158050
publisher
Elsevier
external identifiers
  • scopus:85097768800
ISSN
0925-8388
DOI
10.1016/j.jallcom.2020.158050
language
English
LU publication?
yes
id
aa9f17d7-628c-4838-a89e-58b4d8dc501d
date added to LUP
2020-12-14 09:22:49
date last changed
2022-04-26 22:31:35
@article{aa9f17d7-628c-4838-a89e-58b4d8dc501d,
  abstract     = {{The nature of the non-magnetic to paramagnetic transition of Co3+ oxide LaCoO3 was strongly disputed in the literature for many decades from a low-spin (LS) state below 20 K and to a mixed LS state and high-spin (HS) state or an intermediate-spin (IS) state above 100 K. In this context, the layered perovskite LaSrCoO4 is more favorable for a Jahn-Teller-active IS state because of an elongated distortion, but has been scarcely studied with experimental X-ray spectroscopies as a function of temperature or external pressure. Here, our Co-L2,3 X-ray absorption spectroscopic study indicates a mixture of 40% HS-Co3+ and 60% LS-Co3+ for LaSrCoO4 against 25% HS-Co3+ and 75% LS-Co3+ for LaCoO3 at 300 K and ambient pressure (AP). At 10 K, we observed a sizable magnetic-circular-dichroism signal and a clear HS state of the magnetic Co3+ ion from the Co-L2,3 edge of LaSrCoO4. This result demonstrates that the HS state is already populated in the ground state versus a pure LS ground state in LaCoO3. A quantitative change of quantum number of the spin of the Co3+ ion of LaSrCoO4 as a function of pressure and temperature investigated systematically with Co-Kβ X-ray emission experiments firmly demonstrates not only a mixed state of LS/HS at 300 K and AP but also a presence of the pure LS-Co3+ and HS-Co3+ states only under high pressure and high temperature, respectively.}},
  author       = {{Haw, Shu Chih and Hu, Zhiwei and Lin, Hong Ji and Lee, Jenn Min and Ishii, Hirofumi and Hiraoka, Nozomu and Meléndez-sans, Anna and Komarek, Alexander C. and Tjeng, Liu Hao and Chen, Kai and Luo, Chen and Radu, Florin and Te Chen, Chien and Chen, Jin-ming}},
  issn         = {{0925-8388}},
  language     = {{eng}},
  month        = {{11}},
  publisher    = {{Elsevier}},
  series       = {{Journal of Alloys and Compounds}},
  title        = {{Unusual mixed spin-state of Co3+ in the ground state of LaSrCoO4: Combined high-pressure and high-temperature study}},
  url          = {{http://dx.doi.org/10.1016/j.jallcom.2020.158050}},
  doi          = {{10.1016/j.jallcom.2020.158050}},
  year         = {{2020}},
}