Abstract
Recently, ammonia-thermal reaction has been used for molecular intercalation in layered FeSe, resulting a new Li x (NH 3) y Fe 2 Se 2 superconductor with T c ∼ 45 K. Here, we have used temperature dependent extended x-ray absorption fine structure (EXAFS) to investigate local atomic displacements in single crystals of this new superconductor. Using polarized EXAFS at Fe K-edge we have obtained direct information on the local Fe-Se and Fe-Fe bondlengths and corresponding mean square relative displacements (MSRD). We find that the Se-height in the intercalated system is lower than the one in the binary FeSe, suggesting compressed FeSe 4 tetrahedron in the title system. Incidentally, there is hardly any effect of the intercalation on the bondlengths characteristics, revealed by the Einstein temperatures, that are similar to those found in the binary FeSe. Therefore, the molecular intercalation induces an effective compression and decouples the FeSe slabs. Furthermore, the results reveal an anomalous change in the atomic correlations across T c, appearing as a clear decrease in the MSRD, indicating hardening of the local lattice mode. Similar response of the local lattice has been found in other families of superconductors, e.g., A15-type and cuprates superconductors. This observation suggests that local atomic correlations should have some direct correlation with the superconductivity.
| Original language | English |
|---|---|
| Article number | 27646 |
| Journal | Scientific Reports |
| Volume | 6 |
| DOIs | |
| Publication status | Published - Jun 9 2016 |
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Temperature dependent local atomic displacements in ammonia intercalated iron selenide superconductor. / Paris, E.; Simonelli, L.; Wakita, Takanori; Marini, C.; Lee, J. H.; Olszewski, W.; Terashima, Kensei; Kakuto, T.; Nishimoto, N.; Kimura, T.; Kudo, Kazutaka; Kambe, Takashi; Nohara, Minoru; Yokoya, Takayoshi; Saini, N. L.
In: Scientific Reports, Vol. 6, 27646, 09.06.2016.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Temperature dependent local atomic displacements in ammonia intercalated iron selenide superconductor
AU - Paris, E.
AU - Simonelli, L.
AU - Wakita, Takanori
AU - Marini, C.
AU - Lee, J. H.
AU - Olszewski, W.
AU - Terashima, Kensei
AU - Kakuto, T.
AU - Nishimoto, N.
AU - Kimura, T.
AU - Kudo, Kazutaka
AU - Kambe, Takashi
AU - Nohara, Minoru
AU - Yokoya, Takayoshi
AU - Saini, N. L.
PY - 2016/6/9
Y1 - 2016/6/9
N2 - Recently, ammonia-thermal reaction has been used for molecular intercalation in layered FeSe, resulting a new Li x (NH 3) y Fe 2 Se 2 superconductor with T c ∼ 45 K. Here, we have used temperature dependent extended x-ray absorption fine structure (EXAFS) to investigate local atomic displacements in single crystals of this new superconductor. Using polarized EXAFS at Fe K-edge we have obtained direct information on the local Fe-Se and Fe-Fe bondlengths and corresponding mean square relative displacements (MSRD). We find that the Se-height in the intercalated system is lower than the one in the binary FeSe, suggesting compressed FeSe 4 tetrahedron in the title system. Incidentally, there is hardly any effect of the intercalation on the bondlengths characteristics, revealed by the Einstein temperatures, that are similar to those found in the binary FeSe. Therefore, the molecular intercalation induces an effective compression and decouples the FeSe slabs. Furthermore, the results reveal an anomalous change in the atomic correlations across T c, appearing as a clear decrease in the MSRD, indicating hardening of the local lattice mode. Similar response of the local lattice has been found in other families of superconductors, e.g., A15-type and cuprates superconductors. This observation suggests that local atomic correlations should have some direct correlation with the superconductivity.
AB - Recently, ammonia-thermal reaction has been used for molecular intercalation in layered FeSe, resulting a new Li x (NH 3) y Fe 2 Se 2 superconductor with T c ∼ 45 K. Here, we have used temperature dependent extended x-ray absorption fine structure (EXAFS) to investigate local atomic displacements in single crystals of this new superconductor. Using polarized EXAFS at Fe K-edge we have obtained direct information on the local Fe-Se and Fe-Fe bondlengths and corresponding mean square relative displacements (MSRD). We find that the Se-height in the intercalated system is lower than the one in the binary FeSe, suggesting compressed FeSe 4 tetrahedron in the title system. Incidentally, there is hardly any effect of the intercalation on the bondlengths characteristics, revealed by the Einstein temperatures, that are similar to those found in the binary FeSe. Therefore, the molecular intercalation induces an effective compression and decouples the FeSe slabs. Furthermore, the results reveal an anomalous change in the atomic correlations across T c, appearing as a clear decrease in the MSRD, indicating hardening of the local lattice mode. Similar response of the local lattice has been found in other families of superconductors, e.g., A15-type and cuprates superconductors. This observation suggests that local atomic correlations should have some direct correlation with the superconductivity.
UR - http://www.scopus.com/inward/record.url?scp=84974589103&partnerID=8YFLogxK
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U2 - 10.1038/srep27646
DO - 10.1038/srep27646
M3 - Article
AN - SCOPUS:84974589103
VL - 6
JO - Scientific Reports
JF - Scientific Reports
SN - 2045-2322
M1 - 27646
ER -