Structural transitions and related fluctuations in La1.875-xSmxSr0.125CuO4

Y. Koyama, Y. Wakabayashi, S. I. Nakamura, Y. Inoue, K. Shinohara

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Abstract

Features of both structural transitions and related fluctuations in La1.875-xSmxSr0.125CuO4 have been examined by means of electron diffraction in a temperature range between about 600 K and about 20 K. As the temperature is lowered, a structural phase transition from a high-temperature tetragonal (HTT) structure to a low-temperature orthorhombic (LTO) one takes place in 0≤x≤0.2 and HTT→LTO→Pccn→LTT successive transitions in 0.3≤x≤0.4 where the Pccn and low-temperature tetragonal (LTT) structures are characterized as a rotation of an oxygen octahedron about two 110 directions. An enhancement of a structural fluctuation in the LTO phase, which indicates a soft-phonon mode in the LTO-to-Pccn transition, occurs on cooling even in 0≤x≤0.2 as well as in 0.3≤x≤0.4. Because an increase in the Sm content results in two effects, a lowering of Tc and an enhancement of the structural fluctuation, the fluctuation is understood to suppress the superconductivity. Eventually, a dip in a composition dependence of Tc in La-Sr-Cu-O, which was experimentally found by Oda et al. [J. Phys. Soc. Jpn. 58, 1137 (1989)], is concluded to be due to the structural fluctuation related to the LTO-to-Pccn transition.

Original languageEnglish
Pages (from-to)9710-9716
Number of pages7
JournalPhysical Review B
Volume48
Issue number13
DOIs
Publication statusPublished - 1993 Jan 1

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ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Koyama, Y., Wakabayashi, Y., Nakamura, S. I., Inoue, Y., & Shinohara, K. (1993). Structural transitions and related fluctuations in La1.875-xSmxSr0.125CuO4. Physical Review B, 48(13), 9710-9716. https://doi.org/10.1103/PhysRevB.48.9710