Vortex bound state of a Kondo lattice coupled to a compensated metal
Vortex bound state of a Kondo lattice coupled to a compensated metal
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DOI：
10.1103/physrevb.102.064505
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发表时间：
2020-05
影响因子：
3.7
通讯作者：
S. Iimura;M. Hirayama;S. Hoshino
中科院分区：
文献类型：
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作者：
S. Iimura;M. Hirayama;S. Hoshino
本文从理论上研究了与补偿金属耦合的近藤晶格全能隙超导态中涡旋核低能准粒子激发的物理性质。基于超导态的平均场描述，数值求解紧束缚哈密顿量的Bogoliubov-de Gennes（BdG）方程。孤立涡旋的特征在于其长度尺度与相互作用的大小无关，并且核束缚态的能级与体能隙的能级是同一数量级。这些性质与传统的s波超导体形成强烈对比。为了获得更深入的认识，我们还考虑了连续极限下的有效哈密顿量，并建立了传导电子准经典绿色函数的理论框架。利用Kramer-Pesch近似，我们解析地导出了描述准粒子激发的谱函数，这与数值计算是一致的。结果表明，涡旋束缚态的性质与正常自能和反常自能的奇频特性密切相关，奇频特性与频率的倒数成正比。
We theoretically study physical properties of the low-energy quasiparticle excitations at the vortex core in the full-gap superconducting state of the Kondo lattice coupled to compensated metals. Based on the mean-field description of the superconducting state, we numerically solve the Bogoliubov-de Gennes (BdG) equations for the tight-binding Hamiltonian. The isolated vortex is characterized by a length scale independent of the magnitude of the interaction and the energy level of the core bound state is the same order as the bulk gap. These properties are in strong contrast to the conventional s-wave superconductor. To gain further insights, we also consider the effective Hamiltonian in the continuous limit and construct the theoretical framework of the quasiclassical Green's function of conduction electrons. With the use of the Kramer-Pesch approximation, we analytically derive the spectral function describing the quasiparticle excitations which is consistent with the numerics. It has been revealed that the properties of the vortex bound state are closely connected to the characteristic odd frequency dependence of both the normal and anomalous self-energies which is proportional to the inverse of frequency.