Strong correlations make high-temperature superconductors robust against disorder

Garg, Arti; Randeria, Mohit; Trivedi, Nandini

doi:10.1038/nphys1026

Cited by 86 publications

(113 citation statements)

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“…[15,16] By contrast, for non-magnetic disorder the s± superconducting state is largely immune to disorder, in agreement with earlier one-band studies, finding that correlations enhance the screening of disorder potentials and thereby reduce pair-breaking and scattering rates compared to the non-interacting case. [17][18][19][20][21] In the current multi-orbital case, however, additional impuritygenerated bound states play an important unexpected role in supporting T c . This resilience to non-magnetic disorder is remarkable since favorable clusters of impurities locally pin magnetic order, eventually causing a volume-full inhomogeneous magnetic state which coexists with superconductivity.…”

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confidence: 73%

Unconventional Disorder Effects in Correlated Superconductors

2016

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The understanding of disorder has profoundly influenced the development of condensed matter physics, explaining such fundamental effects as, for example, the transition from ballistic to diffusive propagation, and the presence of quantized steps in the quantum Hall effect. For superconductors, the response to disorder reveals crucial information about the internal gap symmetries of the condensate, and thereby the pairing mechanism itself. The destruction of superconductivity by disorder is traditionally described by Abrikosov-Gorkov (AG) theory, [1,2] which however ignores spatial modulations and ceases to be valid when impurities interfere, and interactions become important. Here we study the effects of disorder on unconventional superconductors in the presence of correlations, and explore a completely different disorder paradigm dominated by strong deviations from standard AG theory due to generation of local bound states and cooperative impurity behavior driven by Coulomb interactions. Specifically we explain under which circumstances magnetic disorder acts as a strong poison destroying high-T c superconductivity at the sub-1% level, and when non-magnetic disorder, counter-intuitively, hardly affects the unconventional superconducting state while concomitantly inducing an inhomogeneous full-volume magnetic phase. Recent experimental studies of Fe-based superconductors (FeSC) have discovered that such unusual disorder behavior seem to be indeed present in those systems.For cuprates, heavy-fermions, and FeSC the study of disorder currently constitutes a very active line of research, motivated largely by the fact that these systems are made superconducting by "chemical disordering" (charge doping), but also boosted by controversies of the correct microscopic model, and a rapid development of local experimental probes. [3][4][5] Focusing on multiband FeSC, disorder studies have proven exceptionally rich and strongly material dependent.[6] Scanning tunneling spectroscopy found a plethora of exotic atomicsized impurity-generated states, [7][8][9][10] NMR and neutrons observed clear evidence of glassy magnetic behavior, [11,12] and µSR discovered magnetic phases generated by non-magnetic disorder. [13,14] The resulting complex inhomogeneous phases and their properties in terms of thermodynamics and transport constitute an important open problem in the field.Here, we present a theoretical study of correlationdriven emergent impurity behavior of both magnetic and nonmagnetic disorder in unconventional s± multi-band superconductors. For the case of magnetic disorder, we find that correlations anti-screen the local moment, and significantly enhance the inter-impurity RudermanKittel-Kasuya-Yosida (RKKY) exchange interactions by inducing non-local long-range magnetic order which operates as an additional competitor to superconductivity. This results in an aggressive T c suppression rate where superconductivity is wiped out by sub-1% concentrations of disorder. This mechanism explains the "poisoning effect" discovered in ...

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confidence: 73%

Unconventional Disorder Effects in Correlated Superconductors

2016

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“…Figure 1b displays the results of the same study, but for the correlated d-wave superconductor with U/t = 2.5. The remarkable result is that even for 25% disorder, the Hubbard correlations "protect" the d-wave V-shaped DOS [15]. The origin of this universal low-energy behavior is the suppressed charge modulations near the impurities as shown in Fig.…”

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confidence: 91%

“…Recently, the effect of strong correlations of this type on the density of states (DOS) of a disordered d-wave superconductor was investigated by Garg et al [15], in an approach where the Gutzwiller approximation was used to approximately project out the doubly occupied states of a disordered t− J model. They found the rather remarkable result that the low-energy states were "protected" by interactions, i.e.…”

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confidence: 99%

“…We first focus on the DOS of the disordered d-wave superconductor in the presence of correlations and compare with the results of Ref. [15]. In particular, we would like to ascertain whether the onset of the local magnetic state has a qualitative effect on the total DOS.…”

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confidence: 99%

“…1c. Therefore, an impurity potential apparently disturbs a correlated superconductor much less than a conventional BCS state [15]. Interestingly, impurities which only modulate the pair interaction will also perturb the electronic structure primarily near the antinodes, while protecting the low-energy DOS universality.…”

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confidence: 99%

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Breakdown of Universal Transport in Correlatedd-Wave Superconductors

Andersen

Hirschfeld

2008

Phys. Rev. Lett.

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Topology and Symmetry in Quantum Materials

2022

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Interest in topological materials continues to grow unabated in view of their conceptual novelties as well as their potential as platforms for transformational new technologies. Electronic states in a topological material are robust against perturbations and support unconventional electromagnetic responses. The first‐principles band‐theory paradigm has been a key player in the field by providing successful prediction of many new classes of topological materials. This perspective presents a cross section through the recent work on understanding the role of geometry and topology in generating topological states and their responses to external stimuli, and as a basis for connecting theory and experiment within the band theory framework. In this work, effective strategies for topological materials discovery and impactful directions for future topological materials research are also commented.

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Strong correlations make high-temperature superconductors robust against disorder

Cited by 86 publications

References 28 publications

Unconventional Disorder Effects in Correlated Superconductors

Unconventional Disorder Effects in Correlated Superconductors

Breakdown of Universal Transport in Correlatedd-Wave Superconductors

Topology and Symmetry in Quantum Materials

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