arXiv subjects

Yoichi Asada

Publications and source records attributed to Yoichi Asada.

9 recordsLinked to original sources

arXiv2006

Conductance of nano-systems with interactions coupled via conduction electrons: Effect of indirect exchange interactions

A nano-system in which electrons interact and in contact with Fermi leads gives rise to an effective one-body scattering which depends on the presence of other scatterers in the attached leads. This non local effect is a pure many-body effect that one neglects when one takes non interacting models for describing quantum transport. This enhances the non-local character of the quantum conductance by exchange interactions of a type similar to the RKKY-interaction between local magnetic moments. A theoretical study of this effect is given assuming the Hartree-Fock approximation for spinless fermions in an infinite chain embedding two scatterers separated by a segment of length L\_c. The fermions interact only inside the two scatterers. The dependence of one scatterer onto the other exhibits oscillations which decay as 1/L\_c and which are suppressed when L\_c exceeds the thermal length L\_T. The Hartree-Fock results are compared with exact numerical results obtained with the embedding method and the DMRG algorithm.

cond-mat.mes-hall↗

arXiv2006

Numerical calculation of the Landauer conductance through an interacting electron system in the Hartree-Fock approximation

We develop a new numerical method to calculate the Landauer conductance through an interacting electron system in the first order perturbation or in the self-consistent Hartree-Fock approximation. It is applied to one and two dimensional systems with nearest-neighbor electron-electron interaction.

cond-mat.mes-hall↗

arXiv2006

Possible Anderson transition below two dimensions in disordered systems of noninteracting electrons

We investigate the possibility of an Anderson transition below two dimensions in disordered systems of non-interacting electrons with symplectic symmetry. Numerical analysis of energy level statistics and conductance statistics on Sierpinski carpets with spin-orbit coupling indicates the occurrence of an Anderson transition below two dimensions.

cond-mat.dis-nn↗

arXiv2005

Quantum transport phenomena in disordered electron systems with spin-orbit coupling in two dimensions and below

Electron transport phenomena in disordered electron systems with spin-orbit coupling in two dimensions and below are studied numerically. The scaling hypothesis is checked by analyzing the scaling of the quasi-1D localization length. A logarithmic increase of the mean conductance is also confirmed. These support the theoretical prediction that the two dimensional metal in systems with spin-orbit coupling has a perfect conductivity. Transport through a Sierpinski carpet is also reported.

cond-mat.mes-hall↗

arXiv2004

Anderson transition in the three dimensional symplectic universality class

We study the Anderson transition in the SU(2) model and the Ando model. We report a new precise estimate of the critical exponent for the symplectic universality class of the Anderson transition. We also report numerical estimation of the $β$ function.

cond-mat.dis-nn↗

arXiv2004

Numerical estimation of the $β$-function in 2D systems with spin-orbit coupling

We report a numerical study of Anderson localization in a 2D system of non-interacting electrons with spin-orbit coupling. We analyze the scaling of the renormalized localization length for the 2D SU(2) model and estimate its $β$-function over the full range from the localized to the metallic limits.

cond-mat.dis-nn↗

arXiv2003

The Anderson transition due to random spin-orbit coupling in two-dimension

We report an analysis of the Anderson transition in an SU(2) model with chiral symmetry. Clear single parameter scaling behaviour is observed. We estimate the critical exponent for the divergence of the localization length to be $ν=2.72\pm.02$ indicating that the transition belongs to the symplectic universality class.

cond-mat.dis-nn↗

arXiv2003

The chiral symplectic universality class

We report a numerical investigation of localization in the SU(2) model without diagonal disorder. At the band center, chiral symmetry plays an important role. Our results indicate that states at the band center are critical. States away from the band center but not too close to the edge of the spectrum are metallic as expected for Hamiltonians with symplectic symmetry.

cond-mat.dis-nn↗

arXiv2002

The Anderson Transition in Two-Dimensional Systems with Spin-Orbit Coupling

We report a numerical investigation of the Anderson transition in two-dimensional systems with spin-orbit coupling. An accurate estimate of the critical exponent $ν$ for the divergence of the localization length in this universality class has to our knowledge not been reported in the literature. Here we analyse the SU(2) model. We find that for this model corrections to scaling due to irrelevant scaling variables may be neglected permitting an accurate estimate of the exponent $ν=2.73 \pm 0.02$.

cond-mat.dis-nn↗