Dropping an impurity into a Chern insulator: A polaron view on topological matter

Camacho-Guardián, Arturo; Goldman, Nathan; Massignan, Pietro; Bruun, Georg M.

doi:10.1103/physrevb.99.081105

Cited by 29 publications

(23 citation statements)

References 62 publications

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“…The polaron formed in the cold-atom systems has been intensely studied where a lattice model is absent similar to the Frohlich model, but the polaron formed in a lattice model (atomic lattice or the crystal lattice) has been less studied, especially the topological [1,2] or chiral systems. In this paper, we focus on the properties of fermion polaron formed in a three-dimensional (3D) doped parabolic system in the crystal lattice.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, we focus on the properties of fermion polaron formed in a three-dimensional (3D) doped parabolic system in the crystal lattice. Considering the effect of impurities (in coherent background), the polaron as an excited quasiparticle in the population/spin-imbalanced Fermi gases, BEC, or the topological insulator [2,3,4], are important when the many-body effect is been taken into account. Unlike the gapless Dirac system where the electron-electron interaction usually gives rise to the renormalization of quasiparticle velocity [5,6], for systems with quadratic dispersion, the electron-electron interaction usually gives rise to the effective mass renormalization [7], which will be discussed in this paper, and we note that the effective mass approximation [8,9,10] is applicable for the polaron in small momentum regime.…”

Section: Introductionmentioning

confidence: 99%

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Attractive polaron formed in doped nonchiral/chiral parabolic system within ladder approximation

2020

Physica B: Condensed Matter

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We investigate the properties of attractive polaron formed by a single impurity dressed with the particle-hole excitations in a three-dimensional (3D) doped (extrinsic) parabolic system. Base on the single particle-hole variational ansatz, we study the pair propagator, self-energy, and the non-self-consistent medium T -matrix. The non-self-consistent T -matrix discussed in this paper contains only the open channel since we don't consider the shift of center-of-mass due to the resonance (e.g., induced by the magnetic field). Besides, since we focus on the low-density regime of the majority particles, the effective Fermi wave vector is small. The scattering form factor is discussed in detail for the chiral case and compared to the non-chiral one. The effects of the bare coupling strength, which is momentum-cutoff-dependent, are also discussed. We found that the pair propagator and the related quantities, like the self-energy, spectral function, induced effective mass, and residue (spectral weight), all exhibit different features in the low-momentum regime and the high one, which also related to the polaronic instabilities as well as the many-body fluctuation and nonadiabatic/adiabatic dynamics. The pair-propagator and the energy relaxation time at finite temperature are also explored.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Attractive polaron formed in doped nonchiral/chiral parabolic system within ladder approximation

2020

Physica B: Condensed Matter

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“…Here we focus on the case where the impurity binds to an additional quasiparticle excitation [33]. Recently a similar situation has been discussed where a mobile impurity is dressed with particle-hole excitations of a Chern insulator [47], resembling the formation of fermi polarons [48][49][50] but in the presence of non-trivial band topology.…”

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confidence: 99%

Topological polarons, quasiparticle invariants, and their detection in one-dimensional symmetry-protected phases

2019

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In the presence of symmetries, one-dimensional quantum systems can exhibit topological order, which in many cases can be characterized by a quantized value of the many-body geometric Zak or Berry phase. We establish that this topological Zak phase is directly related to the Zak phase of an elementary quasiparticle excitation in the system. By considering various systems, we establish this connection for a number of different interacting phases including: the Su-Schrieffer-Heeger model, p-wave topological superconductors, and the Haldane chain. Crucially, in contrast to the bulk many-body Zak phase associated with the ground state of such systems, the topological invariant associated with quasiparticle excitations (above this ground-state) exhibit a more natural route for direct experimental detection. To this end, we build upon recent work [Nature Communications 7, 11994 (2016)] and demonstrate that mobile quantum impurities can be used, in combination with Ramsey interferometry and Bloch oscillations, to directly measure these quasiparticle topological invariants. Finally, a concrete experimental realization of our protocol for dimerized Mott insulators in ultracold atomic systems is discussed and analyzed.

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“…However, when the interactions between two smallsize polarons are taken into account as in the magnetite [58] at finite temperature, the polaron is more delocalized even in the presence of electron-phonon coupling. Recently, the polaron formed in the surface state of a topological material has also been discussed [59,14,60,61]. The polaron in the surface state of topological insulator or the topological crystalline insulator may have stronger delocalization against the disorders due to the protection from the average symmetries [62], which will be discussed detailly in another place.…”

Section: B: Possible Self-localization and The Short-range Potential mentioning

confidence: 99%

Electronic properties and polaronic dynamics of semi-Dirac system within Ladder approximation

2020

Phys. Scr.

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We investigate the electronic properties of the semi-Dirac system and its polaronic dynamics when coupled with a fermi bath with quadratic dispersion. The electronic anisotropic transport properties and the semiclassical dynamics of the semi-Dirac system are studied, including the density-of-states, conductivity, transport relaxation rate, specific heat, electrical current denity, and free energy. The attractive polaron formed as the semi-Dirac impurity dressed with the particle-hole excitations in a two-dimensional system are studied both analytically and numerically. The pair propagator, self-energy, spectral function are being detailly calculated and discussed. The method of medium T -matrix approximation (non-self-consistent), which equivalent to the partially dressed interaction vertex by summing over all ladder diagrams, is applied, and compared with some other methods (for many-body problem), like the leading-order 1/N expansion (GW approximation), Hartree-Fock theory, and the Nozieres-Schmitt-Rink theory. Since we foucs on the weak-coupling region, the mean-field approximation is also applicable. The polaron properties is related to the anisotropic effective masses of the semi-Dirac system. That's in contrast to the polarons formed in the surface of normal Dirac systems which has an isotropic dispersion, since the anisotropic dispersion of the semi-Dirac systems results in anisotropic effective mass and anisotropic charge carrier transport. Besides, the symmetry between electron and hole is also broken since the effective masses of the electron and hole are different, which are affected by the polaronic effect when the semi-Dirac material is deposited on a polar substrate, like hBN. The self-localization, short-range potential, and experimental methods as well as the possible formation of the bose polaron on the surface of semi-Dirac system are also discussed in the end. Our results are useful also for the investigation of two/three-dimensional bosonic polaron as well as the polarons in other solid state systems, like the magnetic matter or the topological systems. *

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Dropping an impurity into a Chern insulator: A polaron view on topological matter

Cited by 29 publications

References 62 publications

Attractive polaron formed in doped nonchiral/chiral parabolic system within ladder approximation

Attractive polaron formed in doped nonchiral/chiral parabolic system within ladder approximation

Topological polarons, quasiparticle invariants, and their detection in one-dimensional symmetry-protected phases

Electronic properties and polaronic dynamics of semi-Dirac system within Ladder approximation

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