A gauge invariant dressed holon and spinon description of the normal-state of underdoped cuprates

A partial charge-spin separation fermion-spin theory is developed to study the normal-state properties of the underdoped cuprates. In this approach, the physical electron is decoupled as a gauge invariant dressed holon and spinon, with the dressed holon behaving like a spinful fermion, and represents the charge degree of freedom together with the phase part of the spin degree of freedom, while the dressed spinon is a hard-core boson, and representing the amplitude part of the spin degree of freedom. The electron local constraint for single occupancy is satisfied. Within this approach, the charge and spin dynamics of the underdoped cuprates are studied based on the t-t'-J model. It is shown that the charge dynamics is mainly governed by the scattering from the dressed holons due to the dressed spinon fluctuation, while the scattering from the dressed spinons due to the dressed holon fluctuation dominates the spin dynamics.Comment: 10 pages, 7 figures, corrected typo

Magnetic properties of spin-1/2 Fermi gases with ferromagnetic interaction

We investigate the magnetic properties of spin-$1/2$ charged Fermi gases with ferromagnetic coupling via mean-field theory, and find the interplay among the paramagnetism, diamagnetism and ferromagnetism. Paramagnetism and diamagnetism compete with each other. When increasing the ferromagnetic coupling the spontaneous magnetization occurs in a weak magnetic field. The critical ferromagnetic coupling constant of the paramagnetic phase to ferromagnetic phase transition increases linearly with the temperature. Both the paramagnetism and diamagnetism increase when the magnetic field increases. It reveals the magnetization density $\bar M$ increases firstly as the temperature increases, and then reaches a maximum. Finally the magnetization density $\bar M$ decreases smoothly in the high temperature region. The domed shape of the magnetization density $\bar M$ variation is different from the behavior of Bose gas with ferromagnetic coupling. We also find the curve of susceptibility follows the Curie-Weiss law, and for a given temperature the susceptibility is directly proportional to the Land\'{e} factor.Comment: 7 pages, 7 figure

Charge transport in underdoped bilayer cuprates

Within the t-J model, we study the charge transport in underdoped bilayer cuprates by considering the bilayer interaction. Although the bilayer interaction leads to the band splitting in the electronic structure, the qualitative behavior of the charge transport is the same as in the case of single layer cuprates. The conductivity spectrum shows a low-energy peak and the unusual midinfrared band. This midinfrared band is suppressed severely with increasing temperatures, while the resistivity in the heavily underdoped regime is characterized by a crossover from the high temperature metallic-like to the low temperature insulating-like behaviors, which are consistent with the experiments.Comment: 5 pages, Revtex, three figures are include

Gauge invariant dressed holon and spinon in doped cuprates

We develop a partial charge-spin separation fermion-spin theory implemented the gauge invariant dressed holon and spinon. In this novel approach, the physical electron is decoupled as the gauge invariant dressed holon and spinon, with the dressed holon behaviors like a spinful fermion, and represents the charge degree of freedom together with the phase part of the spin degree of freedom, while the dressed spinon is a hard-core boson, and represents the amplitude part of the spin degree of freedom, then the electron single occupancy local constraint is satisfied. Within this approach, the charge transport and spin response of the underdoped cuprates is studied. It is shown that the charge transport is mainly governed by the scattering from the dressed holons due to the dressed spinon fluctuation, while the scattering from the dressed spinons due to the dressed holon fluctuation dominates the spin response.Comment: 8 pages, Revtex, three figures are include