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Criticality across the energy spectrum from random artificial gravitational lensing in two-dimensional Dirac superconductors

Ghorashi, Sayed Ali Akbar; Karcher, Jonas F.; Davis, Seth M.; Foster, Matthew S.

Abstract:
We numerically study weak, random, spatial velocity modulation ["quenched gravitational disorder" (QGD)] in two-dimensional massless Dirac materials. QGD couples to the spatial components of the stress tensor; the gauge-invariant disorder strength is encoded in the quenched curvature. Although expected to produce negligible effects, wave interference due to QGD transforms all but the lowest-energy states into a quantum-critical "stack" with universal, energy-independent spatial fluctuations. We study five variants of velocity disorder, incorporating three different local deformations of the Dirac cone: flattening or steepening of the cone, pseudospin rotations, and nematic deformation (squishing) of the cone. QGD should arise for nodal excitations in the d-wave cuprate superconductors (SCs), due to gap inhomogeneity. Our results may explain the division between low-energy "coherent" (plane-wave-like) and finite-energy "incoherent" (spatially inhomogeneous) excitations in the SC and pseudogap regimes. The model variant that best matches the cuprate phenomenology possesses quenched random pseudospin rotations and nematic fluctuations. ... mehr



Zugehörige Institution(en) am KIT Institut für Theorie der Kondensierten Materie (TKM)
Institut für Nanotechnologie (INT)
Institut für Quantenmaterialien und -technologien (IQMT)
Publikationstyp Forschungsbericht/Preprint
Publikationsjahr 2020
Sprache Englisch
Identifikator KITopen-ID: 1000124795
Umfang 23 S.
Vorab online veröffentlicht am 25.06.2020
Nachgewiesen in arXiv
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