TY - JOUR

T1 - Correlations and confinement of excitations in an asymmetric Hubbard ladder

AU - Abdelwahab, Anas

AU - Jeckelmann, Eric

N1 - Funding information: This work was done as part of the Research Units Metallic nanowires on the atomic scale: Electronic and vibrational coupling in real world systems (FOR1700) of the German Research Foundation (DFG) and was supported by grant JE 261/1-2. The DMRG calculations were carried out on the cluster system at the Leibniz University of Hannover and at the Sudan Center for HPC and Grid Computing.

PY - 2018/9/17

Y1 - 2018/9/17

N2 - Correlation functions and low-energy excitations are investigated in the asymmetric two-leg ladder consisting of a Hubbard chain and a noninteracting tight-binding (Fermi) chain using the density matrix renormalization group method. The behavior of charge, spin and pairing correlations is discussed for the four phases found at half filling, namely, Luttinger liquid, Kondo-Mott insulator, spin-gapped Mott insulator and correlated band insulator. Quasi-long-range antiferromagnetic spin correlations are found in the Hubbard leg in the Luttinger liquid phase only. Pair-density-wave correlations are studied to understand the structure of bound pairs found in the Fermi leg of the spin-gapped Mott phase at half filling and at light doping but we find no enhanced pairing correlations. Low-energy excitations cause variations of spin and charge densities on the two legs that demonstrate the confinement of the lowest charge excitations on the Fermi leg while the lowest spin excitations are localized on the Hubbard leg in the three insulating phases. The velocities of charge, spin, and single-particle excitations are investigated to clarify the confinement of elementary excitations in the Luttinger liquid phase. The observed spatial separation of elementary spin and charge excitations could facilitate the coexistence of different (quasi-)long-range orders in higher-dimensional extensions of the asymmetric Hubbard ladder.

AB - Correlation functions and low-energy excitations are investigated in the asymmetric two-leg ladder consisting of a Hubbard chain and a noninteracting tight-binding (Fermi) chain using the density matrix renormalization group method. The behavior of charge, spin and pairing correlations is discussed for the four phases found at half filling, namely, Luttinger liquid, Kondo-Mott insulator, spin-gapped Mott insulator and correlated band insulator. Quasi-long-range antiferromagnetic spin correlations are found in the Hubbard leg in the Luttinger liquid phase only. Pair-density-wave correlations are studied to understand the structure of bound pairs found in the Fermi leg of the spin-gapped Mott phase at half filling and at light doping but we find no enhanced pairing correlations. Low-energy excitations cause variations of spin and charge densities on the two legs that demonstrate the confinement of the lowest charge excitations on the Fermi leg while the lowest spin excitations are localized on the Hubbard leg in the three insulating phases. The velocities of charge, spin, and single-particle excitations are investigated to clarify the confinement of elementary excitations in the Luttinger liquid phase. The observed spatial separation of elementary spin and charge excitations could facilitate the coexistence of different (quasi-)long-range orders in higher-dimensional extensions of the asymmetric Hubbard ladder.

KW - cond-mat.str-el

UR - http://www.scopus.com/inward/record.url?scp=85053433834&partnerID=8YFLogxK

U2 - 10.1140/epjb/e2018-90360-9

DO - 10.1140/epjb/e2018-90360-9

M3 - Article

VL - 91

JO - European Physical Journal B

JF - European Physical Journal B

SN - 1434-6028

IS - 9

M1 - 207

ER -