Interplay between charge, magnetic, and superconducting order in a Kondo lattice with attractive Hubbard interaction
Interplay between charge, magnetic, and superconducting order in a Kondo lattice with attractive Hubbard interaction
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DOI：
10.1103/physrevb.98.195111
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发表时间：
2018-09
影响因子：
3.7
通讯作者：
B. Lechtenberg;R. Peters;N. Kawakami
中科院分区：
文献类型：
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作者：
B. Lechtenberg;R. Peters;N. Kawakami
研究了重费米子S波超导体的超导电性、电荷有序、磁有序和近藤效应之间的竞争，该超导体由具有吸引力的在位Hubbard相互作用的近藤晶格模型描述.该模型采用实空间动力学平均场理论进行求解。为此，我们在Nambu空间中发展了一个数值重整化群(NRG)框架，用于解决超导杂质问题。这个扩展的NRG方案还允许SU(2)自旋对称性破缺解，使我们能够研究$S$波超导和无公度自旋密度波之间的竞争或合作。在半填充状态下，我们发现了一个有趣的阶段，在这个阶段，电子的磁有序提升了电荷密度波(CDW)态和超导态之间的简并，导致超导电性的强烈抑制。此外，在此参数范围内，系统也可能成为半金属。远离半填充，CDW消失，取而代之的是超导与无公度SDW的结合，直到适度的Kondo耦合到$f$-电子。我们发现，由于近藤屏蔽的抑制，CDW和超导都增强了磁有序。
We investigate the competition between superconductivity, charge-ordering, magnetic-ordering, and the Kondo effect in a heavy fermion $s$-wave superconductor described by a Kondo lattice model with an attractive on-site Hubbard interaction. The model is solved using the real-space dynamical mean field theory. For this purpose, we develop a numerical renormalization group (NRG) framework in Nambu space, which is used to solve the superconducting impurity problem. This extended NRG scheme also allows for SU(2) spin symmetry broken solutions, enabling us to examine the competition or cooperation between $s$-wave superconductivity and incommensurate spin-density waves (SDWs). At half filling, we find an intriguing phase where the magnetic ordering of the $f$-electrons lifts the degeneracy between the charge density wave (CDW) state and the superconducting state, leading to a strong suppression of superconductivity. In addition, the system may also become a half metal in this parameter regime. Away from half filling, the CDWs vanish and are replaced by superconductivity combined with incommensurate SDWs up to moderate Kondo couplings to the $f$-electrons. We find that both CDWs as well as superconductivity enhance magnetic ordering due to the suppression of Kondo screening.