Disorder in interacting quasi-one-dimensional systems: Flat and dispersive bands
Disorder in interacting quasi-one-dimensional systems: Flat and dispersive bands
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DOI：
10.1103/physrevb.108.035131
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发表时间：
2023-02
影响因子：
3.7
通讯作者：
Minpeng Liang;Yong Yang;Chen Cheng;R. Mondaini
中科院分区：
文献类型：
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作者：
Minpeng Liang;Yong Yang;Chen Cheng;R. Mondaini
利用密度矩阵重整化群方法研究了无序准一维系统中的超导体-绝缘体跃迁。重点关注四分之一填充时相互作用的旋向哈密顿量的情况，我们对比了当母非相互作用模型具有平坦带或色散带时在SIT中产生的差异。此外，通过比较保持或不保持SU(2)对称的失序分布，我们揭示了触发绝缘行为的临界失序振幅。虽然标度分析表明所有模型（两个晶格和两种无序类型）的过渡都是Berezinskii-Kosterlitz-Thouless型，但只有在具有Zeeman-like无序的平带模型中，临界无序是不消失的。从这个意义上说，平带结构确实增强了超导性。对于平面带模型和色散带模型，i)在SU(2)对称随机化学势的存在下，单重态对的无序诱导跃迁是从超导体到绝缘体；ii)对于zeeman型失序，从超导体到非成对费米子的绝缘体的转变。在所有情况下，我们的数值结果表明没有中间无序驱动的金属相。
We investigate the superconductor-insulator transition (SIT) in disordered quasi-one dimensional systems using the density-matrix renormalization group method. Focusing on the case of an interacting spinful Hamiltonian at quarter-filling, we contrast the differences arising in the SIT when the parent non-interacting model features either flat or dispersive bands. Furthermore, by comparing disorder distributions that preserve or not SU(2)-symmetry, we unveil the critical disorder amplitude that triggers insulating behavior. While scaling analysis suggests the transition to be of a Berezinskii-Kosterlitz-Thouless type for all models (two lattices and two disorder types), only in the flat-band model with Zeeman-like disorder the critical disorder is nonvanishing. In this sense, the flat-band structure does strengthen superconductivity. For both flat and dispersive band models, i) in the presence of SU(2)-symmetric random chemical potentials, the disorder-induced transition is from superconductor to insulator of singlet pairs; ii) for the Zeeman-type disorder, the transition is from superconductor to insulator of unpaired fermions. In all cases, our numerical results suggest no intermediate disorder-driven metallic phase.