基于La2CuO4的超导体中的氧同位素效应和结构相变
Science (New York, N.Y.)
|December 7, 1990
概括
铜酸超导体中的氧同位素效应与结构相变密切相关. 这表明电子对格子不稳定性的贡献是这些材料超导性的关键.
科学领域:
- 材料科学 材料科学 材料科学
- 凝聚物质物理学 凝聚物质物理学
- 固态化学 固态化学
背景情况:
- 铜中的超导过渡温度 (Tc) 对同位素成分敏感.
- 氧同位素效应 (alpha(o)) 提供了对超导体配对机制的见解.
研究的目的:
- 研究La2-xSrxCuO(4) 和La2-xBaxCuO(4) 中氧同位素效应的兴奋剂依赖性.
- 探索这些材料中同位素效应,结构相变和超导之间的关系.
主要方法:
- 在La2-x(Sr,Ba) xCuO(4) 中 (Sr) 和 (Ba) 兴奋剂 (x) 的系统变化.
- 测量氧同位素对超导过渡温度的影响 (alpha(o)).
- 同步射线X射线衍射分析结构参数和相变.
主要成果:
- 在Sr和Ba兴奋剂化合物中,在x=0.12附近观察到的最大α (o) 值 (>0.5).
- 网格参数或与高αo) 材料中的同位素交换发生的极小变化.
- 异常alpha(o) 行为,结构阶段过渡 (Abm到P4(2) /ncm) 和兴奋剂水平之间的相关性.
结论:
- 同位素效应的异常兴奋剂依赖性与结构相变的接近有关.
- 静态结构扭曲不会导致观察到的大同位素效应.
- 这意味着电子对晶格不稳定性的贡献,每个Cu原子的峰值为~1/8孔.
- 在基于La(2) CuO(4) 的系统中,洞 doping,CuO(6) 八面体倾斜不稳定性和超导性之间存在着强烈的联系.
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