Type-II Dirac semimetal stabilized by electron-phonon coupling

Möller, Mirko; Sawatzky, G. A.; Franz, Marcel; Berciu, Mona

doi:10.1038/s41467-017-02442-y

Cited by 31 publications

(26 citation statements)

References 48 publications

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“…Lattice dimerization in one-dimension was initially described by the Su-Schrieffer-Heeger (SSH) model 1 , in which the atomic motion modulates the overlap integrals between neighboring atoms. Recently, SSH-like models have attracted further attention due to the fact that they can produce highly mobile polarons with light effective masses 9 , generate robust phonon-mediated pairing 10 , and even stabilize and control the location of a type-II Dirac point 11 . SSH interactions are also believed to be dominant mechanism for electron-phonon (e-ph) interactions in materials like the high-T c cuprates 12,13 .…”

Section: Introductionmentioning

confidence: 99%

Quantum Monte Carlo study of lattice polarons in the two-dimensional three-orbital Su–Schrieffer–Heeger model

Johnston

2020

npj Quantum Mater.

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The electron-lattice interaction gives rise to a rich set of phenomena in quantum materials. Microscopically, this interaction often arises from the modulation of orbital overlaps; however, many theoretical studies neglect such couplings. Here, we present an exact diagonalization and determinant quantum Monte Carlo study of a three-orbital Su-Schrieffer-Heeger (SSH) model, on a twodimensional Lieb lattice and in the negative charge transfer regime. At half-filling (one hole/unit cell), we observe a bipolaron insulating phase with a bond-disproportionate lattice. This phase is robust against moderate hole doping but is suppressed at large hole concentrations, leading to a metallic polaron-liquid-like state with fluctuating patches of local distortions. We also find an s-wave superconducting state at large hole doping that primarily appears on the oxygen sublattice. Our work provides a nonperturbative view of SSH-type couplings in two dimensions with implications for materials where such couplings are dominant.

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Section: Introductionmentioning

confidence: 99%

Quantum Monte Carlo study of lattice polarons in the two-dimensional three-orbital Su–Schrieffer–Heeger model

Johnston

2020

npj Quantum Mater.

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“…In contrast to type-I Weyl semimetals, type-II materials feature 'tilted' Weyl cones [12], which result in a non-vanishing density of states at E F . These materials exhibit a variety of exotic quantum phenomena [13,14], including superconductivity, large anisotropic magnetoresistance, and recently, in WP 2 , viscous electron transport. The interplay between topological properties and electronic interactions has been the focus of recent work on this material [15].…”

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confidence: 99%

Microscopic origins of hydrodynamic transport in the type-II Weyl semimetal WP2

2018

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The origins of hydrodynamic transport in strongly interacting Dirac and Weyl semimetals have remained elusive in theoretical descriptions and experimental measurements. We investigate the structure and microscopic properties of transport in WP 2 , a type-II Weyl semimetal, to probe the emergence of hydrodynamic phenomena. We characterize the quantum behavior underlying the hydrodynamic transport regime as a function of temperature through ab initio calculations of the relevant microscopic scattering processes, including electron-phonon, electron-electron, and phonon-mediated electron-electron lifetimes. We present a fundamentally new approach to calculate phonon-drag, a mechanism that is invoked in numerous recent experiments, and remains the subject of active debate in the field. Further, we show unique and unexpected features of the lifetime-resolved Fermi surfaces of WP 2 in the hydrodynamic regime and quantify the degree of anisotropy in electron and hole pockets. This description of the microscopic dynamics in hydrodynamic systems like WP 2 indicates the importance of electron-phonon interactions in understanding connections between transport in hydrodynamic materials and strongly correlated quantum systems including unconventional metals and high Tc superconductors.

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“…It has been shown previously that only smooth crossovers are allowed in the model with diagonal coupling [4]. Sharp polaron transitions have been found in the models where the off-diagonal interaction or the sum of diagonal and off-diagonal ones are taken into account [5][6][7][8][9][10][11][12][13][14]. All transitions found are controlled by the parameters of the electron-phonon interaction.…”

Section: Introductionmentioning

confidence: 76%

“…However, their origin is not necessarily the result of the transition between the large and small polaron states. This may occur, for example, due to the multiband contributions [10] or even due to the level crossing in polaron spectra [12].…”

Section: Introductionmentioning

confidence: 99%

Polaron transformations in the realistic model of the strongly correlated electron system

et al. 2020

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Electron-phonon coupling, diagonal in a real space formulation, leads to a polaron paradigm of smoothly varying properties. However, fundamental changes, namely the singular behavior of polarons, occur if offdiagonal pairing is involved into consideration. The study of polaron transformations and related properties of matter is of particular interest for realistic models, since competition between diagonal and off-diagonal electron-phonon contributions in the presence of other strong interactions can result in unconventional behavior of the system. Here we consider a two-dimensional multiband pd model of cuprate superconductors with electron-phonon interaction and analyze the features of the systems that are caused by the competition of diagonal and off-diagonal electron-phonon contributions in the limit of strong electron correlations. Using the polaronic version of the generalized tight-binding method, we describe the evolution of the band structure, Fermi surface, density of states at Fermi level, and phonon spectral function in the space of electron-phonon parameters ranging from weak to strong coupling strength of the adiabatic limit. On the phase diagram of polaron properties we reveal two quantum phase transitions and show how electron-phonon interaction gives rise to Fermi surface transformation (i) from hole pockets to true Fermi arcs and (ii) from hole to electron type of conductivity. We also demonstrate the emergence of new states in the phonon spectral function of the polaron and discuss their origin.

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Type-II Dirac semimetal stabilized by electron-phonon coupling

Cited by 31 publications

References 48 publications

Quantum Monte Carlo study of lattice polarons in the two-dimensional three-orbital Su–Schrieffer–Heeger model

Quantum Monte Carlo study of lattice polarons in the two-dimensional three-orbital Su–Schrieffer–Heeger model

Microscopic origins of hydrodynamic transport in the type-II Weyl semimetal WP2

Polaron transformations in the realistic model of the strongly correlated electron system

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