Scanning tunneling microscopy studies on Zhang-Rice singlet state and high-TィイD2cィエD2 superconductivity

张莱斯单线态和高T2D2超导的扫描隧道显微镜研究

基本信息

批准号：
09440126
负责人：
ODA Migaku
金额：
$ 6.53万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

In the present study, we have been obtained the following results.1) In Bi2212 and La214, the low temperature (T<<TィイD2cィエD2) energy gap 2ΔィイD2oィエD2 increases with the lowering of the hole doping level p and scales with pseudogap temperature TィイD1*ィエD1 over a wide p range; TィイD1*ィエD1 is comparable to the mean-fieid TィイD2cィエD2(TィイD2coィエD2). This result provides a strong evidence for the pseudogap being related to the high-TィイD2cィエD2 superconductivity.2) On the basis of the dependences of electronic specific heat and magnetic susceptibility, it was found that the superconducting critical fluctuation develops markedly below a certain temperature TィイD2sf' ィエD2, 〜20% higher than TィイD2cィエD2 and much lower than TィイD1*ィエD1〜TィイD2coィエD2. This suggests that the motion of singlet pairs, whose formation will give rise to the pseudogap below 〜TィイD1*ィエD1, tends to become coherent below 〜TィイD2sfィエD2 to establish long-range phase coherence at TィイD2cィエD2.3) In Bi2212 and La214, TィイD2cィエD2 nearly scales with pΔィイD2oィエD2 ; kィイD2BィエD2TィイD2cィエD2〜pΔィイD2oィエD2. This indicates that the energy scale in determining TィイD2cィエD2, is of the order of pΔィイD2oィエD2, which is a striking feature of high-TィイD2cィエD2 cuprates, differing from that expected in conventional superconductors.In the present study, a scenario for the superconducting transition mechanism has also been proposed on the basis of the results mentioned above.

在本研究中，我们得到了以下结果：1）在Bi2212和La214中，低温（T<<T D2c D2）能隙2Δ D2 D2随着空穴掺杂水平p的降低而增加，并且与赝能隙成比例。较宽 p 范围内的温度 D1*D1；D1*D1 与平均场相当； T2D2cD2(T2D2coD2)这一结果为赝能隙与高T2D2cD2超导性的关系提供了强有力的证据。2)根据电子比热和磁化率的依赖性，发现超导临界涨落明显低于T2D2cD2。某个温度 T2sf' D2，比 T2sf' D2 高约 20% TyD2cD2 且远低于 TiD1*D1〜TiiD2coD2，这表明单重态对的运动（其形成将在〜Tii D1*D1 以下产生赝能隙）趋向于在〜T2D2sfD2 以下变得相干，以在处建立长程相位相干性。 T2D2cD2.3) 在 Bi2212 和La214，TiD2cD2 几乎与 pΔD2oD2 成比例；TyD2cD2 的量级为 pΔD2oD2，这是高 TD2cD2 的显着特征铜酸盐，与传统超导体中预期的不同。在本研究中，基于上述结果还提出了超导转变机制的方案。