Pairing in spinless fermions and spin chains with next-nearest neighbor interactions

Gotta, Lorenzo; Mazza, Leonardo; Simon, Pascal; Roux, Guillaume

doi:10.1103/physrevresearch.3.013114

Cited by 13 publications

(8 citation statements)

References 58 publications

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“…The fact that a paired phase and an unpaired phase should be separated by a second-order phase transition with emergent critical properties and a central charge c = 3/2 is crucial for linking pairing to Majorana modes [31,35]. This prediction has been verified by several numerical analyses [33,34,36,37]. Yet, in a recent article, we have shown that this need not always be the case [60].…”

Section: Introductionmentioning

confidence: 54%

“…Reminder on the case U1 = 0 It has already been shown that the Hamiltonian in Eq. (1) at t = U 1 = 0 can be diagonalised exactly by mapping the model to an effective XX spin chain [37,56,68] and can be interpreted as a paired phase P π . We now briefly review the argument.…”

Section: A Overview On the Limit T T U1mentioning

confidence: 99%

“…Pairing phenomena have been identified in several onedimensional lattice models of spinless fermions [33][34][35][36][37]. A paradigmatic way of inducing pairing is through densitydensity interactions, which could be either short ranged or with tails which decay algebraically (see e.g.…”

Section: Introductionmentioning

confidence: 99%

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Two-fluid coexistence and phase separation in a one dimensional model with pair hopping and density interactions

Gotta,

Mazza,

Simon

et al. 2021

Preprint

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We compute the phase diagram of a one-dimensional model of spinless fermions with pair-hopping and nearest-neighbor interaction, first introduced by Ruhman and Altman, using the density-matrix renormalization group combined with various analytical approaches. Although the main phases are a Luttinger liquid of fermions and a Luttinger liquid of pairs, we also find remarkable phases in which only a fraction of the fermions are paired. In such case, two situations arise: either fermions and pairs coexist spatially in a two-fluid mixture, or they are spatially segregated leading to phase separation. These results are supported by several analytical models that describe in an accurate way various relevant cuts of the phase diagram. Last, we identify relevant microscopic observables that capture the presence of these two fluids: while originally introduced in a phenomenological way, they support a wider application of two-fluid models for describing pairing phenomena.

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Section: Introductionmentioning

confidence: 54%

Section: A Overview On the Limit T T U1mentioning

confidence: 99%

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Two-fluid coexistence and phase separation in a one dimensional model with pair hopping and density interactions

Gotta,

Mazza,

Simon

et al. 2021

Preprint

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“…Forming trimers composed of a unique fermionic speciespin-polarized fermions -is particularly challenging despite seminal results in the context of the quantum Hall effect [34]. The pairing of spinless fermions already shows a rich phenomenology [35][36][37][38][39][40][41][42][43][44][45], and it is a crucial mechanism for some topological phases of matter, motivating further investigations in this direction. An intuitive route is to use attractive density interactions [42] on a chain and stabilize trimers using a third neighbor repulsion to prevent phase separation.…”

mentioning

confidence: 99%

Kinetic formation of trimers in a spinless fermionic chain

Gotta,

Mazza,

Simon

et al. 2021

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We show the stabilization of two trimer phases in a chain of spinless fermions with a correlated hopping term. A trimer fluid forms due to a gain in trimer kinetic energy and competes with a fluid of unbound fermions. Furthermore, we observe two intermediate phases where these two fluids coexist and do not spatially separate. Depending on the way trimers are created out of the Fermi sea, hybridization can occur, in which case the onset of correlations between the two fluids is well captured by a generalized BCS ansatz. These results are finally extended to the formation of larger multimers, which highlights the peculiarities of pair and trimer formation.

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“…to verify that its single-particle excitations are gapped. As a further marker of fermion pairing [29][30][31][32], we calculate the Fourier transform of the fluctuations of the local density, FT [δ n−,j ]. In the case of strong interactions, we additionally find it useful to analyze the densitydensity correlation function across the diagonal links of the ladder in the original two-band basis…”

mentioning

confidence: 99%

Superconducting pairing from repulsive interactions of fermions in a flat-band system

Mahyaeh¹,

Köhler²,

Black‐Schaffer³

et al. 2021

Preprint

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Fermion systems with flat bands can boost superconductivity by enhancing the density of states at the Fermi level. We use quasiexact numerical methods to show that repulsive interactions between spinless fermions in a one-dimensional (1D) flat-band system, the Creutz ladder, give a finite pairing energy that increases with repulsion, though charge quasi-order (QO) remains dominant. Adding an attractive component shifts the balance in favor of superconductivity and the interplay of two flat bands further yields a remarkable enhancement of superconductivity, well outside of known paradigms for 1D fermions.

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Pairing in spinless fermions and spin chains with next-nearest neighbor interactions

Cited by 13 publications

References 58 publications

Two-fluid coexistence and phase separation in a one dimensional model with pair hopping and density interactions

Two-fluid coexistence and phase separation in a one dimensional model with pair hopping and density interactions

Kinetic formation of trimers in a spinless fermionic chain

Superconducting pairing from repulsive interactions of fermions in a flat-band system

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