It is shown that the Hubbard chain in a magnetic field of arbitrary strength H can be treated as a liquid of interacting pseudoparticles which at T=0 has only forward scattering. The excitation spectra can be understood in terms of particle-hole processes in the pseudoparticle renormalized bands. Within this framework, we are able to study in detail the low-temperature thermodynamics of the Hubbard model. Explicit expressions for the specific heat ${\mathit{c}}_{\mathit{v}}$ for a nearly half-filled band and for values of the magnetic field close to the ferromagnetic saturated state are derived. The renormalized charge and spin masses which regulate the crossover regime to the exponential behavior of several physical quantities close to the metal-insulator and ferromagnetic transitions, respectively, are calculated.

• Received 19 April 1991

DOI:https://doi.org/10.1103/PhysRevB.44.9967