0.7Structure Of Conductance Quantization In Quantum Point Contact

The mesoscopic system is seen macroscopical in size, however it has showed obviouscharacteristic of quantum. Phase coherence of electrons in the transport process lead to somenovel physical phenomena. The most remarkable quantum phenomenon is the conductancequantization effect: the conductance exhibits plateaus at integral multiples ofG₀=2e²/h. In1996, Thomas et al. observed an additional plateau at0.7G₀in quantum point contact in theabsence of any magnetic field. This anomaly has aroused people’s great attention due to itcannot give an explanation using the single-electron model. The reason about thisphenomenon has yet a reasonable explanation and most researchers think the reason it appearsis generally related to electron-electron interaction and spin now.In the paper, we study the reason of0.7structure in theory. Our numerical approach isbased on the Green’s function technique which is evaluated at the Hartree-Fork level. Aninitial spin-polarization is triggered by applying an initial small magnetic field. We reproducerelevant features of this anomaly when the strength of electron-electron interaction haschanged. We obtain the obvious spin accumulation by the calculation of the electron density.Finally, we calculate the noise factor in zero temperature. The shot noise is suppressed atconductance values around0.7G₀which accounts for the differently transmitting channels inthat range. Though we reproduce0.7G₀dependence on an initial spin-polarization, wecalculate how electron-electron interaction affects0.7structure in a simple method. We expectour conclusion could provide some opinions to spin relevant transport and further reveal newphysical phenomenon.