摘要
研究了Rashba自旋轨道耦合作用下的二维无限长条形样品中的电子输运,计算了样品的霍尔电导和纵向电阻,得到了完整的整数量子霍尔效应.在一定强磁场范围内,由于样品两边缘的限制,能级在大波矢范围快速上升,在小波矢范围形成平坦的朗道能级.强磁场下自旋轨道耦合完全解除自旋简并.位于朗道能级上升和下降区域的电子形成传输电流.计算结果表明,霍尔电导呈现台阶型,平台出现在e2/h的整数倍位置,形成霍尔平台.温度对霍尔平台的电导有一定影响.在某临界温度以下,霍尔平台电导可以达到10–9以上的精度.最后分析了声子发射和吸收产生整数量子霍尔效应的纵向电阻的机制,近似计算了弛豫时间,得到了纵向电阻.结果表明,纵向电阻在霍尔平台区域为零,而在霍尔平台之间出现峰值.
Electron transport mechanism of a two-dimensional infinite slab subjected to Rashba spin-orbital coupling is studied in this paper.We calculate the Hall conductance and the longitudinal resistance of the integer quantum Hall effect(IQHE).In a strong magnetic field,the Landau levels of electrons increase rapidly at large wave vectors due to the constraint of the two edges of the sample while they remain flat at small wave vectors.Although the Zeeman effect can split the energy levels of spin degeneracy under a strong magnetic field,the spacing between the Landau levels is exactly equal to the spin splitting,thus the spin degeneracies have not been fully resolved.The spin-orbital coupling fully resolves the spin degeneracies of the energy levels.This is the key to reproducing the IQHE.Electrons with rapid increasing energies are localized at the two edges of the sample and transport along the edges to form separated currents with opposite directions.In this case,back scattering of electrons is prohibited due to the localization of these two branches.Since the electrons on the upper and lower edges originate respectively from the left and right electrode,they also have the chemical potentials of the electrons in those electrodes,respectively.The computation result shows that the Hall conductance appears as plateaus at integer times of e2/h.Temperature influences the accuracy of the Hall plateaus.As an international resistance standard,exceeding a critical temperature can produce significant errors to the Hall plateaus.Below the critical temperature,the accuracy can reach 10–9.Finally the mechanism of the longitudinal resistance of the IQHE is discussed and computed numerically.It is shown that only the wavefunctions with opposite and small wave vectors have a significant overlap in the bulk of the sample and thus contribute to the longitudinal resistance.Due to the separation of currents in different directions in space,the longitudinal resistance does vanish at the Hall plateaus but it appears when the Hall condu
作者
梁滔
李铭
Liang Tao;Li Ming(Key Laboratory of Quantum Engineering and Quantum Materials of Guangdong Province,School of Physics and Telecommunication Engineering,South China Normal University,Guangzhou 510006,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2019年第11期220-226,共7页
Acta Physica Sinica
关键词
自旋轨道耦合
整数量子霍尔效应
电子输运
spin-orbital coupling
integer quantum Hall effect
electron transport
