Spectral properties of quasiparticle excitations induced by magnetic moments in superconductors
Spectral properties of quasiparticle excitations induced by magnetic moments in superconductors
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DOI：
10.1103/physrevb.55.12648
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发表时间：
1997-05-01
影响因子：
3.7
通讯作者：
Schrieffer, JR
中科院分区：
文献类型：
--
作者：
Salkola, MI;Balatsky, AV;Schrieffer, JR
探讨了超导体中局域化的经典磁矩的后果，并研究了它们对能隙内束缚态光谱性质的影响。在临界磁矩之上，在s波超导体中磁杂质附近会自发产生局域化的准粒子激发，引发零温量子相变。在此相变中，基态的自旋量子数从0变为1/2，而总电荷保持不变。相比之下，当正常态能谱具有粒子 - 空穴对称性时，发现d波超导体的自旋非极化基态对于任何磁矩值都是稳定的。依据清洁超导体的相关对称性来解释杂质散射对准粒子态的影响。比较了非自洽（T矩阵）方法和自洽平均场近似所得到的结果，发现在相干长度大于费米长度的区域内，两种方案在定性上是一致的。
The consequences of localized, classical magnetic moments in superconductors are explored and their effect on the spectral properties of the intragap bound states is studied. Above a critical moment, a localized quasiparticle excitation in an s-wave superconductor is spontaneously created near a magnetic impurity, inducing a zero-temperature quantum transition. In this transition, the spin quantum number of the ground state changes from zero to 1/2, while the total charge remains the same. In contrast, the spin-unpolarized ground state of a d-wave superconductor is found to be stable for any value of the magnetic moment when the normal-state energy spectrum possesses particle-hole symmetry. The effect of impurity scattering on the quasiparticle states is interpreted in the spirit of relevant symmetries of the clean superconductor. The results obtained by the non-self-consistent (T matrix) and the self-consistent mean-field approximations are compared and qualitative agreement between the two schemes is found in the regime where the coherence length is longer than the Fermi length.