Spin and charge excitations of the degenerate Hubbard model in one dimension

Journal Article · Fri Feb 01 04:00:00 EST 1991 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.43.3101· OSTI ID:5619326

Schlottmann, P ^[1]

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1. Department of Physics, Temple University, Philadelphia, Pennsylvania 19122 (US)

The degenerate Hubbard chain with {ital N} internal degrees of freedom is integrable if site occupations of more than two electrons are excluded. The ground state of the model has several unusual properties; e.g., the magnetic susceptibility has logarithmic singularities as the field {ital H}{r arrow}0 and also the specific-heat coefficient is singular. An extensive discussion of ground-state properties as a function of {ital U} and the band filling is presented. The elemental charge and spin excitations are derived for arbitrary {ital U} and band filling. If, on average, there is exactly one electron per site as a function of {ital U}, a qualitative change in the low-energy charge excitations is found at a critical value {ital U}{sub {ital c}}. This change is probably associated with a Mott metal-insulator transition ({ital U}{sub {ital c}}=0 for {ital N}=2). The Fermi velocity is finite for {ital U}{lt}{ital U}{sub {ital c}} but vanishes for {ital U}{gt}{ital U}{sub {ital c}} (for one electron per site). The spin-wave velocity is inversely proportional to the magnetic susceptibility for all {ital U} and band fillings. There are {ital N}{minus}1 elemental spin-wave branches. For arbitrary band filling there are then {ital N}{minus}1 soft modes at different finite momenta, all related to the Fermi surface. For exactly one electron per site, the spin-excitation spectrum can be mapped onto the one of the SU({ital N}) Heisenberg chain. The implications of the hole states on superconductivity are also discussed.

• DOE Contract Number: FG02-87ER45333
• OSTI ID: 5619326
• Journal Information: Physical Review, B: Condensed Matter; (USA), Journal Name: Physical Review, B: Condensed Matter; (USA) Vol. 43:4; ISSN PRBMD; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

656100* -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CHARGE STATE
COLLECTIVE EXCITATIONS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITATION
GROUND STATES
HIGH-TC SUPERCONDUCTORS
ONE-DIMENSIONAL CALCULATIONS
SPIN WAVES
SUPERCONDUCTORS