Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Enhanced superconductivity and various edge modes in modulated $t$-$J$
  chains   We numerically investigate the ground state of the extended $t$-$J$
Hamiltonian with periodic local modulations in one dimension by using the
density-matrix renormalization group method. Examining charge and spin
excitation gaps, as well as the pair binding energy, with extrapolated results
to the thermodynamic limit, we obtain a rich ground-state phase diagram
consisting of the metallic state, the superconducting state, the phase
separation, and insulating states at commensurate fillings. Compared to the
homogeneous 1D $t$-$J$ model, the superconductivity is greatly enhanced and
stabilized by the flat-band structure. This superconducting state in
quasi-periodic chains shares similar properties with ladder systems:
significant negative pair binding energy occurs, and the singlet pairing
correlation function dominates with the algebraic decay while the
single-particle Green's function and spin correlation function decay
exponentially. On the other hand, quasi-periodicity leads to nontrivial
topological nature in insulating states, characterized by different integer
Chern numbers at different fillings. Due to the interplay among the topology,
the interaction, and the 1D confinement, gapless edge modes show strong
spin-charge separation and in different regions can relate to different
collective modes, which are the charge of a single fermion, the magnon, and the
singlet-pair. We also find two interaction driven topological transitions: i)
at particle filling $\rho=1/2$, the low-energy edge excitations change from the
magnon to singlet-pair, accompanied with pair formation in bulk; and ii) at
$\rho=3/4$, while the gapless edge mode remains the charge of a single fermion,
there is a gap-closing point and a $\pi$-phase shift in the quasi-particle
spectrum.

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The categories of this paper are: gr-qc
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The categories of this paper are: mtrl-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: q-fin
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The categories of this paper are: hep-ex
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The categories of this paper are: hep-ph
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The categories of this paper are: nlin
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The categories of this paper are: eess
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The categories of this paper are: patt-sol
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The categories of this paper are: atom-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: funct-an
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The categories of this paper are: alg-geom
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The categories of this paper are: plasm-ph
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The categories of this paper are: econ
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The categories of this paper are: math-ph