TY - JOUR

T1 - Single-pole ladder at quarter filling

AU - Aristov, D. N.

AU - Kiselev, M. N.

AU - Kikoin, K.

PY - 2007/6/7

Y1 - 2007/6/7

N2 - We study the ground state and excitation spectrum of a quasi-one- dimensional system consisting of a pole and rungs oriented in opposite directions ("centipede ladder," CL) at quarter filling. The spin and charge excitation spectra are found in the limits of small and large longitudinal hoppings t compared to the on-rung hopping rate t and exchange coupling I. At small t, the system with ferromagnetic on-rung exchange demonstrates instability against dimerization. Coherent propagation of charge-transfer excitons is possible in this limit. At large t, CL behaves like two-orbital Hubbard chain, but the gap opens in the charge excitation spectrum, thus reducing the symmetry from SU(4) to SU(2). The spin excitations are always gapless and their dispersion changes from quadratic magnonlike for ferromagnetic on-rung exchange to linear spinonlike for antiferromagnetic on-rung exchange in weak longitudinal hopping limit.

AB - We study the ground state and excitation spectrum of a quasi-one- dimensional system consisting of a pole and rungs oriented in opposite directions ("centipede ladder," CL) at quarter filling. The spin and charge excitation spectra are found in the limits of small and large longitudinal hoppings t compared to the on-rung hopping rate t and exchange coupling I. At small t, the system with ferromagnetic on-rung exchange demonstrates instability against dimerization. Coherent propagation of charge-transfer excitons is possible in this limit. At large t, CL behaves like two-orbital Hubbard chain, but the gap opens in the charge excitation spectrum, thus reducing the symmetry from SU(4) to SU(2). The spin excitations are always gapless and their dispersion changes from quadratic magnonlike for ferromagnetic on-rung exchange to linear spinonlike for antiferromagnetic on-rung exchange in weak longitudinal hopping limit.

UR - http://www.scopus.com/inward/record.url?scp=34347370913&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.75.224405

DO - 10.1103/PhysRevB.75.224405

M3 - Article

AN - SCOPUS:34347370913

VL - 75

JO - Physical Review B-Condensed Matter

JF - Physical Review B-Condensed Matter

SN - 1098-0121

IS - 22

M1 - 224405

ER -