Effect of molecular intercalation on the local structure of superconducting Nax(NH3)yMoSe2 system

L. Simonelli; E. Paris; T. Wakita; C. Marini; Kensei Terashima; X. Miao; W. Olszewski; N. Ramanan; D. Heinis; Y. Kubozono; T. Yokoya; N. L. Saini

doi:10.1016/j.jpcs.2017.07.011

Effect of molecular intercalation on the local structure of superconducting Na_x(NH₃)_yMoSe₂ system

L. Simonelli, E. Paris, T. Wakita, C. Marini, Kensei Terashima, X. Miao, W. Olszewski, N. Ramanan, D. Heinis, Y. Kubozono, T. Yokoya, N. L. Saini

Research Institute for Interdisciplinary Science

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

1 Citation (Scopus)

Abstract

We have studied the local structure of layered Na_x(NH₃)_yMoSe₂ system by Mo K-edge extended X-ray absorption fine structure (EXAFS) measurements performed as a function of temperature. We find that molecular intercalation in MoSe₂ largely affects the Mo-Se network while Mo-Mo seems to sustain small changes. The Einstein temperature (Θ_E of Mo-Mo distance hardly changes (∼264 K) indicating that bond strength of this distance remains unaffected by intercalation. On the other hand, Mo-Se distance suffers a softening, revealed by the decrease of Θ_E from ∼364 K to ∼350 K. The results indicate that Na⁺ ion transported by NH₃ molecules may enter between the two MoSe-layers resulting reduced Se-Se coupling. Therefore, increased hybridization between Se 4p and Mo 4d orbitals due to inter-layer disorder is the likely reason of metallicity in intercalated MoSe₂ and superconductivity at low temperature.

Original language	English
Pages (from-to)	70-74
Number of pages	5
Journal	Journal of Physics and Chemistry of Solids
Volume	111
DOIs	https://doi.org/10.1016/j.jpcs.2017.07.011
Publication status	Published - Dec 2017

Keywords

Dichalcogenides
Intercalation effect
Local disorder
Superconductivity

ASJC Scopus subject areas

Chemistry(all)
Materials Science(all)
Condensed Matter Physics

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10.1016/j.jpcs.2017.07.011

Cite this

@article{300be36fd4304330b049de4688f67f3c,

title = "Effect of molecular intercalation on the local structure of superconducting Nax(NH3)yMoSe2 system",

abstract = "We have studied the local structure of layered Nax(NH3)yMoSe2 system by Mo K-edge extended X-ray absorption fine structure (EXAFS) measurements performed as a function of temperature. We find that molecular intercalation in MoSe2 largely affects the Mo-Se network while Mo-Mo seems to sustain small changes. The Einstein temperature (ΘE of Mo-Mo distance hardly changes (∼264 K) indicating that bond strength of this distance remains unaffected by intercalation. On the other hand, Mo-Se distance suffers a softening, revealed by the decrease of ΘE from ∼364 K to ∼350 K. The results indicate that Na+ ion transported by NH3 molecules may enter between the two MoSe-layers resulting reduced Se-Se coupling. Therefore, increased hybridization between Se 4p and Mo 4d orbitals due to inter-layer disorder is the likely reason of metallicity in intercalated MoSe2 and superconductivity at low temperature.",

keywords = "Dichalcogenides, Intercalation effect, Local disorder, Superconductivity",

author = "L. Simonelli and E. Paris and T. Wakita and C. Marini and Kensei Terashima and X. Miao and W. Olszewski and N. Ramanan and D. Heinis and Y. Kubozono and T. Yokoya and Saini, {N. L.}",

note = "Funding Information: We thank ALBA staff for the assistance during the measurements. This work was partly supported by Grants-in-Aid for Scientific Research (No. 15H03691) and the Program for Promoting the Enhancement of Research University from MEXT and the Program for Advancing Strategic International Networks to Accelerate the Circulation of Talented Researchers from JSPS (R2705). The work is a part of the executive protocol of the general agreement for cooperation between the Sapienza University of Rome and Okayama University. The work at Sapienza is partially supported by PRIN2012 (grant number 2012X3YFZ2). Publisher Copyright: {\textcopyright} 2017 Elsevier Ltd",

year = "2017",

month = dec,

doi = "10.1016/j.jpcs.2017.07.011",

language = "English",

volume = "111",

pages = "70--74",

journal = "Journal of Physics and Chemistry of Solids",

issn = "0022-3697",

publisher = "Elsevier Limited",

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TY - JOUR

T1 - Effect of molecular intercalation on the local structure of superconducting Nax(NH3)yMoSe2 system

AU - Simonelli, L.

AU - Paris, E.

AU - Wakita, T.

AU - Marini, C.

AU - Terashima, Kensei

AU - Miao, X.

AU - Olszewski, W.

AU - Ramanan, N.

AU - Heinis, D.

AU - Kubozono, Y.

AU - Yokoya, T.

AU - Saini, N. L.

N1 - Funding Information: We thank ALBA staff for the assistance during the measurements. This work was partly supported by Grants-in-Aid for Scientific Research (No. 15H03691) and the Program for Promoting the Enhancement of Research University from MEXT and the Program for Advancing Strategic International Networks to Accelerate the Circulation of Talented Researchers from JSPS (R2705). The work is a part of the executive protocol of the general agreement for cooperation between the Sapienza University of Rome and Okayama University. The work at Sapienza is partially supported by PRIN2012 (grant number 2012X3YFZ2). Publisher Copyright: © 2017 Elsevier Ltd

PY - 2017/12

Y1 - 2017/12

N2 - We have studied the local structure of layered Nax(NH3)yMoSe2 system by Mo K-edge extended X-ray absorption fine structure (EXAFS) measurements performed as a function of temperature. We find that molecular intercalation in MoSe2 largely affects the Mo-Se network while Mo-Mo seems to sustain small changes. The Einstein temperature (ΘE of Mo-Mo distance hardly changes (∼264 K) indicating that bond strength of this distance remains unaffected by intercalation. On the other hand, Mo-Se distance suffers a softening, revealed by the decrease of ΘE from ∼364 K to ∼350 K. The results indicate that Na+ ion transported by NH3 molecules may enter between the two MoSe-layers resulting reduced Se-Se coupling. Therefore, increased hybridization between Se 4p and Mo 4d orbitals due to inter-layer disorder is the likely reason of metallicity in intercalated MoSe2 and superconductivity at low temperature.

AB - We have studied the local structure of layered Nax(NH3)yMoSe2 system by Mo K-edge extended X-ray absorption fine structure (EXAFS) measurements performed as a function of temperature. We find that molecular intercalation in MoSe2 largely affects the Mo-Se network while Mo-Mo seems to sustain small changes. The Einstein temperature (ΘE of Mo-Mo distance hardly changes (∼264 K) indicating that bond strength of this distance remains unaffected by intercalation. On the other hand, Mo-Se distance suffers a softening, revealed by the decrease of ΘE from ∼364 K to ∼350 K. The results indicate that Na+ ion transported by NH3 molecules may enter between the two MoSe-layers resulting reduced Se-Se coupling. Therefore, increased hybridization between Se 4p and Mo 4d orbitals due to inter-layer disorder is the likely reason of metallicity in intercalated MoSe2 and superconductivity at low temperature.

KW - Dichalcogenides

KW - Intercalation effect

KW - Local disorder

KW - Superconductivity

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