Impurity effect as a probe for the pairing symmetry of graphene-based superconductors

Li, Yuan-Qiao; Zhou, Tao

doi:10.1007/s11467-021-1056-y

Cited by 10 publications

(5 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…入磁性的点缺陷 [26−28] , 因此, 理论上可以通过单个磁性杂质附近的局域电子结构来定性模拟晶界附近的电子结构并进一步研究YSR态. 对超导体的单个杂质效应的研究通常有两种有效的方法, 一种是忽略杂质对超导序参量的影响, 近似认为超导序参量均匀分布, 将哈密顿量分为均匀项和杂质项两个部分, 其中均匀部分可以进行傅里叶变换到动量空间, 杂质项可以视作微扰或者一个散射中心处理, 在T矩阵或者微扰论结合戴逊方程的基础上获得系统的格林函数, 进一步可以研究系统的其他性质 [16,17,24] . 这种方法的缺点是忽略了序参量的空间涨落, 尤其是我们通常关心杂质附近的局域特性, 而杂质附近的超导序参量往往被压制了.…”

Section: 理论计算显示在石墨烯材料的晶界附近会引unclassified

Single magnetic impurity effects in graphene based superconductors

Zhao,

Li,

Zhou

2023

Acta Phys. Sin.

Self Cite

View full text Add to dashboard Cite

The magnetic impurity effects and the existence of bound states (i.e. Yu-Shiba-Rusinov states) in superconductors have been a topic of great interest. Recently, the existence of Yu-Shiba-Rusinov states in graphene-based superconducting materials has been successfully observed in the laboratory. This paper establishes an effective Hamiltonian in real space to describe the superconducting state of graphene materials, considering a single magnetic impurity. It constructs the Bogoliubov-de Gennes (BdG) equation and performs self-consistency calculations on the superconducting order parameter. On this basis, the paper theoretically investigates the effects of magnetic impurities on graphene-like superconductors. The calculation results show that the Yu-Shiba-Rusinov state can only appear within the superconducting pairing symmetry of the traditional <i>s</i>-wave pairing. The position and strength of the bound state are related to the magnetic moment of the impurity, and it shows a notable electron-hole asymmetry. There are no bound states in the energy gap for other pairing symmetries. This theoretical calculation not only provides a reasonable explanation for experimental phenomena, but also demonstrates that the heterojunction system composed of graphene and traditional superconductors has an <i>s</i>-wave superconducting pairing induced by the proximity effect in the graphene layer.

show abstract

Section: 理论计算显示在石墨烯材料的晶界附近会引unclassified

Single magnetic impurity effects in graphene based superconductors

Zhao,

Li,

Zhou

2023

Acta Phys. Sin.

Self Cite

View full text Add to dashboard Cite

show abstract

“…The existence of all off-diagonal matrix elements indicates that this disorder correlates different sublattices and spins, through the induced spatial inhomogeneity of the order parameters around the impurities. The self-energy can therefore provide valuable information about the LDOS around impurities through its connection to the LDOS [87]. Since these superconducting phases may be mediated by plasmons in a proximitized metal layer, the corresponding coupling parameters may also be controlled by changing the plasmonic properties of the metal or the distance between the metal and the graphene sheet.…”

Section: Disorder-enhanced P-wave Superconductivitymentioning

confidence: 99%

High-resolution real-space evaluation of the self-energy operator of disordered lattices: Gade singularity, spin–orbit effects and p-wave superconductivity

Lopes

Ferreira

2022

J. Phys. Mater.

View full text Add to dashboard Cite

Disorder is a key factor influencing the behavior of condensed states of matter, however the true extent of its impact is generally difficult to determine due to the prominent roles played by quantum interference, entanglement between spin and orbital degrees of freedom and proximity to quantum critical points. Here we show that the one-particle disorder self-energy --- a direct probe of the renormalization of low-energy excitations due to defects and impurities distributed randomly in a crystal --- can be obtained by means of unbiased spectral expansions of lattice Green's functions in a computationally expedient manner. Our scheme provides a powerful framework to map out the frequency and wavevector dependence of electronic excitations in unprecedented large tight-binding systems, up to $10^{9}$ orbitals, with energy resolution only limited by the mean level spacing. We demonstrate the versatility of our approach in 3 distinct problems: (i) the Gade singularity in honeycomb layers with dilute topological defects; (ii) the rich landscape of impurity resonances in a spin--orbit-coupled ferromagnet; and (iii) the tailoring of emergent $s$-wave and $p$-wave superconducting phases in graphene via atomic defects. These examples reveal rich features in the disorder self-energy $\Sigma_{\textrm{dis}}(\mathbf{k},\omega)$ that are absent from the self-consistent $T$-matrix approach and other common approximation schemes, which include regimes of nontrivial wavevector dependence and anomalous dependence upon the impurity concentration. Our study unravels puzzling, and so far largely inaccessible, manifestations of strong nonperturbative quantum interference effects in quantum materials and disordered phases of matter.

show abstract

Section: Disorder-enhanced P-wave Superconductivitymentioning

confidence: 99%

High-resolution real-space evaluation of the self-energy operator of disordered lattices: Gade singularity, spin-orbit effects and p-wave superconductivity

João,

Lopes,

Ferreira

2021

Preprint

View full text Add to dashboard Cite

Disorder is a prominent factor influencing the fate of condensed phases of matter, yet the true extent of its impact is generally difficult to understand due to the significant role played by quantum interference effects, entanglement between internal spin and orbital degrees of freedom, and proximity to quantum critical points. Here we show that the quasiparticle self-energy-a direct probe of the renormalization of low-energy excitations due to interactions and disorder-can be obtained by means of unbiased, general-purpose polynomially-scaling spectral expansions of lattice Green's functions. Our scheme provides a powerful framework to access the disorder self-energy Σ(k, ω) in unprecedented large tight-binding systems [with up to billions of orbitals (N ≈ 10 9 )] with energy resolution only limited by the mean level spacing. We demonstrate the versatility of our approach in 3 distinct problems: (i) the Gade singularity in the honeycomb lattice with vacancy defects; (ii) impurity resonances in a spin-orbit-coupled ferromagnet and (iii) mixed s-wave and p-wave superconductivity in disordered graphene. Our study unravels striking manifestations of nonperturbative quantum interference effects so far inaccessible to real-space numerical techniques.

show abstract

Impurity effect as a probe for the pairing symmetry of graphene-based superconductors

Cited by 10 publications

References 37 publications

Single magnetic impurity effects in graphene based superconductors

Single magnetic impurity effects in graphene based superconductors

High-resolution real-space evaluation of the self-energy operator of disordered lattices: Gade singularity, spin–orbit effects and p-wave superconductivity

High-resolution real-space evaluation of the self-energy operator of disordered lattices: Gade singularity, spin-orbit effects and p-wave superconductivity

Contact Info

Product

Resources

About