arXiv subjects

S. Fujimoto

Publications and source records attributed to S. Fujimoto.

79 records · Page 5Linked to original sources

arXiv1998

Universal conductance in quantum wires in the presence of Umklapp scattering

The effects of Umklapp scattering on the zero-temperature conductance in one-dimensional quantum wires are reexamined by taking into account both the screening of external potential and the non-uniform chemical potential shift due to electron-electron interaction. It is shown that in the case away from half-filling the conductance is given by the universal value, $2e^2/h$, even in the presence of Umklapp scattering, owing to these renormalization effects of external potential. The conclusion is in accordance with the recent claim obtained for the system with non-interacting leads being attached to a quantum wire.

cond-mat.mes-hall↗

arXiv1995

Exact Critical Properties of the Multi-Component Interacting Fermion Model with Boundaries

Exact critical properties of the one-dimensional SU($N$) interacting fermion model with open boundaries are studied by using the Bethe ansatz method. We derive the surface critical exponents of various correlation functions using boundary conformal field theory. They are classified into two types, i.e. the exponents for the chiral SU($N$) Tomonaga-Luttinger liquid and those related to the orthogonality catastrophe. We discuss a possible application of the results to the photoemission (absorption) in the edge state of the fractional quantum Hall effect.

cond-mat↗

arXiv1995

Exact Finite-Size Spectra in the Kondo Problem and Boundary Conformal Field Theory

The exact finite-size spectra for several quantum impurity models related to the Kondo problem are obtained from the Bethe ansatz solutions. Using the finite-size scaling in boundary conformal field theory, we determine various surface critical exponents from the exact spectrum, which accord with those obtained by Affleck and Ludwig with Kac-Moody fusion rules. Some applications to critical phenomena observed in connection with the orthogonality catastrophe are also discussed.

cond-mat↗

arXiv1995

Exact Critical Exponents for Pseudo-Particles in the Kondo Problem

Exact critical exponents of the Green functions for pseudo-fermions and slave bosons in the SU($N$) Anderson model with $U\rightarrow\infty$ are obtained by using the Bethe ansatz solution and boundary conformal field theory. They are evaluated exactly for mixed valence systems and Kondo systems with crystalline fields. The results agree with the prediction of Menge and Müller-Hartmann, which coincide with those of the X-ray problem. Some implication of our results in one-dimensional chiral systems is also discussed.

cond-mat↗

arXiv1995

Weak-Coupling Approach to Hole-Doped S=1 Haldane Systems

As a weak-coupling analogue of hole-doped $S=1$ Haldane systems, we study two models for coupled chains via Hund coupling; coupled Hubbard chains, and a Hubbard chain coupled with an $S=1/2$ Heisenberg chain. The fixed point properties of these models are investigated by using bosonization and renormalization group methods. The effect of randomness on these fixed points is also studied. It is found that the presence of the disorder parameter inherent in the Haldane state in the former model suppresses the Anderson localization for weak randomness, and stabilizes the Tomonaga-Luttinger liquid state with the spin gap.

cond-mat↗

arXiv1994

Bosonization approach to the one-dimensional Kondo lattice model

The one-dimensional Kondo lattice model is investigated by using bosonization techniques and conformal field theory. In the half-filled band, the charge and spin gaps open for the anti-ferromagnetic Kondo coupling. Away from half-filling, the paramagnetic metallic state is characterized by the fixed point of Tomonaga-Luttinger liquid with the {\it large} Fermi surface in accordance with known results. It is suggested that as the electron density approaches half-filling, both of spin and charge susceptibilities may show a divergence property.

cond-mat↗

arXiv1994

Microscopic Calculations of the Finite-Size Spectrum in the Kondo Problem

The finite-size spectrum in the Kondo problem is obtained from the Bethe-ansatz solution of the exactly solved models. We investigate the Anderson model, the highly correlated SU($ν$) Anderson model and the {\it s-d} exchange model. For all these models we find that the spectra exhibit the properties characteristic of the Fermi liquid fixed point, and hence our microscopic calculations are in accordance with the results obtained by boundary conformal field theory with current algebra symmetry.

cond-mat↗