Structural Instability Associated with the Tilting of CuO_6 Octahedra in La_<2-x>Sr_xCuO_4 : Condensed Matter: Electronic Properties, etc.

概要

論文の詳細を見る
Comprehensive inelastic neutron-scattering measurements were performed to study the soft optical phonons in La_<2-x>Sr_xCuO_4 at x = 0.10, 0.12 and 0.18. We found at x = 0.18 that the softening of Z-point phonon, suggesting incipient structural transition from the low-temperature orthorhombic (LTO) to low-temperature tetragonal (LTT) phase, breaks at T_c, which is consistent with the previous report by Lee et al. for the optimally doped x = 0.15 sample. As for x = 0.10 and 0.12, on the other hand, the softening continues even below T_c. It is thus clarified that the breaking of soft phonon is characteristic of La_<2-x>Sr_xCuO_4 in the optimally and overdoped regions. In the course of studying the soft phonons, we discovered that a central peak remains above the LTO to high-temperature tetragonal (HTT) phase transition at T_<s1> and splits into incommensurate components along the [1 1 0]_<HTT> direction at higher temperatures. This is a common feature for both x = 0.12 and 0.18 and their temperature dependences of the splitting 2 can be scaled by using a renormalized temperature T/T_<s1>. In the high temperature limit, saturates around 0.12 r. l. u., which value is close to the splitting of incommensurate magnetic signals. This implies that the incipient lattice modulation starts appearing at very high temperature. Details of this modulation and its relations with other properties are, however, not yet clarified.
社団法人日本物理学会の論文
2000-03-15

Structural Instability Associated with the Tilting of CuO_6 Octahedra in La_<2-x>Sr_xCuO_4 : Condensed Matter: Electronic Properties, etc.

スポンサーリンク

概要

著者

関連論文

スポンサーリンク