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ID 18781
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creator
Nimori, Shigeki
Sakita, Shigenobu
Nakamura, Fumihiko
Fujita, Toshizo
Hata, Hiroaki
abstract
Using high-quality single crystals of La2-xSrxCuO4, Roman scattering spectra in the (c,c) geometry have been investigated in different Sr concentrations (x=0,0.1,0.113,0,15,0.22) and in the wide temperature region. It has been found that the apical oxygen vibration along the c axis shows the following anomalous behaviors in the dependences of the Sr concentration and temperature. With the increase of the Sr concentration, the peak intensity abruptly decreases from x=0 to 0.1 and its line shape becomes asymmetric. In the temperature dependence, its energy is almost constant or slightly decreases with decreasing temperature, and also its intensity decreases above 100 K universally in the doped samples. In addition, the background intensities increase with increasing x, except for x=0.113 at 6 K, where "1/8 problem" occurs. This increase shows that the background response is caused by an electronic excitation because the magnetic one is forbidden in the (c,c) spectra. The decrease of the background at x=0.113 at 6 K is understood by the formation of charge density wave. The asymmetric line shapes of the apical oxygen vibration are well explained by the Fano model, which is based on the interference effect between the phonon and electronic excitations. Furthermore, the abrupt decrease of the intensity from x=0 to 0.1 is also explained by the introduction of the electron-phonon interaction. The correlation between the obtained electron-phonon interaction and Tc has been found in the Sr-concentration dependence.
journal title
Physical Review B - Condensed Matter and Materials Physics
volume
Volume 62
issue
Issue 6
start page
4142
end page
4147
date of issued
2000-08-01
publisher
American Physical Society
issn
1098-0121
ncid
publisher doi
language
eng
nii type
Journal Article
HU type
Journal Articles
DCMI type
text
format
application/pdf
text version
publisher
rights
Copyright (c) 2000 American Physical Society.
relation url
department
Graduate School of Integrated Arts and Sciences
Graduate School of Advanced Sciences of Matter