Untersuchung der Andreev-Reflexion an Schwer-Fermion (HF)/Supraleiter-Grenzflächen bei tiefen Temperaturen mittels Punktkontaktspektroskopie.

使用点接触光谱研究低温下重费米子 (HF)/超导体界面的安德烈夫反射。

• 批准号: 14065307
• 负责人: Dr. Heiko Stalzer
• 金额: --
• 依托单位: Department of Physics
• 依托单位国家: 德国
• 项目类别: Research Fellowships
• 财政年份: 2005
• 资助国家: 德国
• 起止时间: 2004-12-31 至 2006-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/14065307?language=en
• 关键词: Untersuchung; der; Andreev; Reflexion; Schwer

Strong interactions among the electrons lead in heavy-fermion superconductors (HFS) to strongly enhanced electron masses in comparison to normal metals (N). Due to the nature of the strong electron-electron interactions some HFS compounds show strong evidence that the symmetry of the superconducting wave function corresponds to states with higher angular momentum (p-, d-wave etc.) in comparison to s-wave superconductors, leading to unconventional behavior. Point-contact spectroscopy (PCS) of N/HFS contacts is a strong method to investigate the symmetry and related properties of the superconducting wave function. Unfortunately, up to now the basic process of Andreev reflection (AR) underlying in PCS, which describes the electron-hole conversion at the N/HFS interface, is not understood in detail. Although the magnitude of this process should be strongly suppressed by the large mismatch of the effective electron masses in N and HFS, a significant Andreev signal in the differential conductance versus voltage has been measured in many experiments. It has been proposed that only the effective masses without strong interactions determine the boundary conditions at the N/HFS interface. In search of an effect of the effective electron mass on the Andreev signal, we propose to investigate the reverse configuration, where the heavy-fermion component in the normal conducting state is in contact with a conventional superconductor. Specifically we will use point-contacts consisting of CeColn5 single crystals with different effective masses and conventional superconductors as a counter electrode. The Andreev signal shall be investigated in detail and should enlighten the role of the effective mass in the Andreev reflection process.

与普通金属 (N) 相比，电子之间的强相互作用导致重费米子超导体 (HFS) 的电子质量大大增强。由于强电子-电子相互作用的性质，一些 HFS 化合物显示出强有力的证据，表明与横波超导体相比，超导波函数的对称性对应于具有更高角动量的状态（p 波、d 波等），从而导致非常规行为。 N/HFS 接触的点接触光谱 (PCS) 是研究超导波函数的对称性和相关特性的有力方法。不幸的是，到目前为止，PCS 中描述 N/HFS 界面上的电子-空穴转换的安德烈夫反射 (AR) 的基本过程还没有被详细了解。尽管这个过程的幅度应该被 N 和 HFS 中有效电子质量的巨大失配所强烈抑制，但在许多实验中已经测量到了微分电导与电压之间的显着安德烈夫信号。有人提出，只有没有强相互作用的有效质量才能确定 N/HFS 界面处的边界条件。为了寻找有效电子质量对安德烈夫信号的影响，我们建议研究反向配置，其中正常导电状态的重费米子分量与传统超导体接触。具体来说，我们将使用由具有不同有效质量的CeColn5单晶和传统超导体组成的点接触作为对电极。应详细研究安德烈夫信号，并应阐明有效质量在安德烈夫反射过程中的作用。