在氧化铜接口中通过射击噪声显示的伪间隙状态中的电子配对
Panpan Zhou1, Liyang Chen2, Yue Liu1,3
1Department of Physics and Astronomy, Rice University, Houston, TX, USA.
Nature
|August 23, 2019
概括
研究人员在高温超导体的伪间隙区域内发现了配对电荷载体的证据. 这些发现挑战了现有的伪间隙模型和铜氧化物中的竞争状态.
科学领域:
- 凝聚物质物理学
- 材料科学
背景情况:
- 铜氧化物的高温超导性仍然不太清楚.
- 在临界温度以上的正常状态下的伪间隙阶段是争论的关键领域.
- 现有的理论将伪间隙归因于前体超导,预成对或竞争的顺序.
研究的目的:
- 调查伪空隙中的电荷载体的性质.
- 解决围绕铜氧化物伪缺口的起源的争论.
- 作为温度和偏差的函数来确定载体的电荷.
主要方法:
- 使用原子层对层分子束表层制造高质量的La$_{2-x}$Sr$_{x}$CuO$_{4}$/La$_{2}$CuO$_{4}$/La$_{2-x}$Sr$_{x}$CuO$_{4}$ (LSCO/LCO/LSCO) 异构结构.
- 测量各种兴奋剂水平的穿过这些异构结构的道电流中的射击噪声.
- 在不同偏向电压-温度模式下分析射击噪声数据.
主要成果:
- 在偏向电压-温度空间中确定了三个不同的区域.
- 在超导间隙外,射击噪声表明单个电荷载体的独立道.
- 在超导间隙深处, 增强的射击噪声表明多个Andreev反射.
- 在临界温度以上,扩展到大偏差,噪声水平表明电荷载体的配对,可在伪间隙区域内检测.
结论:
- 在虚空区域深处存在配对的电荷载体挑战了目前的模型.
- 这些发现为解释伪差距和破碎对称状态的理论提供了新的约束.
- 已确定相位波动是限制超导领域的一个因素.
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