CeCoIn $_5$和CeIrIn $_5$的扫描隧道显微镜研究

Tracing crystal-field splittings in the rare earth-based intermetallic CeIrIn$_5$

Crystal electric field states in rare earth intermetallics show an intricate entanglement with the many-body physics that occurs in these systems and that is known to lead to a plethora of electronic phases. Here, we attempt to trace different contributions to the crystal electric field (CEF) splittings in CeIrIn$_5$, a heavy-fermion compound and member of the Ce$M$In$_5$ ($M$= Co, Rh, Ir) family. To this end, we utilize high-resolution resonant angle-resolved photoemission spectroscopy (ARPES) and present a spectroscopic study of the electronic structure of this unconventional superconductor …

Fermionology in the Kondo-Heisenberg model: the case of CeCoIn$_{5}$

Fermi surface of heavy electron systems plays a fundamental role in understanding their variety of puzzling phenomena, for example, quantum criticality, strange metal behavior, unconventional superconductivity and even enigmatic phases with yet unknown order parameters. The spectroscopy measurement of typical heavy fermion superconductor CeCoIn$_{5}$ has demonstrated multi-Fermi surface structure, which has not been in detail studied theoretically in a model system like the Kondo-Heisenberg model. In this work, we make a step toward such an issue with revisiting the Kondo-Heisenberg model. It …

Spatial modulation of a unitary impurity-induced resonances in superconducting CeCoIn$_{5}$

Motivated by recent experimental progress in high-resolution scanning tunneling microscopy (STM) techniques, we propose to investigate the local quasiparticle density of states around a unitary impurity in the heavy fermion superconductor CeCoIn$_{5}$. Based on the T-matrix approach we obtain a sharp nearly zero-energy resonance state (ZERS) in the strong impurity potential scattering localized around the impurity, and find qualitative differences in the spatial pattern of the tunneling conductance modulated by the nodal structure of the superconducting gap. These unique features may be used a…

Unconventional superconductivity in the strong-coupling limit for the heavy fermion system CeCoIn$_5$

We present scanning tunneling spectroscopy measurements of the local quasiparticles' excitation spectra of CeCoIn$_5$ between 440mK and 3K in samples with a bulk $T_{\rm c}=2.25$K. The spectral shape of our low-temperature tunneling data, quite textbook nodal-gap conductance, allow us to confidently fit the spectra with a d-wave density of states considering also a shortening of quasiparticles' lifetime term $Γ$. The $Δ(0)$ value obtained from the fits yields a BCS ratio $2Δ/kT_{\rm c} =7.73$ suggesting that CeCoIn$_5$ is an unconventional superconductor in the strong coupling limit. The fits …

重费米子超导体中的点接触谱学

Point-contact spectroscopy in heavy-fermion superconductors

我们发展了一个极小模型来计算金属针尖与超导重费米子系统之间的点接触谱。我们应用我们的隧道模型的重费米子CeCoIn 5，在正常和超导状态。在点接触和扫描隧道光谱中，许多重费米子材料，如CeCoIn 5，表现出不对称的微分电导dI/dV，并在超导状态下强烈抑制Andreev反射信号。我们认为，这两个功能可以解释在一个多通道隧道模型中存在的局域态界面附近。我们发现，隧道进入两个巡回带的轻，重电子来解释Fano线形状的微分电导是不够的。当电子从点接触的金属尖端隧穿进入重费米子系统时，体中或界面附近的局域态是量子干涉发生的重要组成部分。