Spin splitting of one-dimensional subbands in high quality quantum wires at zero magnetic field
Spin splitting of one-dimensional subbands in high quality quantum wires at zero magnetic field
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零磁场下高质量量子线中一维子带的自旋分裂
DOI：
10.1103/physrevb.62.15842
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发表时间：
2000
影响因子：
3.7
通讯作者：
D. Ritchie
中科院分区：
文献类型：
--
作者：
K. S. Pyshkin;C. Ford;R. Harrell;M. Pepper;E. Linfield;D. Ritchie
我们研究了在未掺杂的GaAs/Al_xGa_（1-x）As异质结构中形成的高质量一维收缩区的输运性质，该结构基本上不受电离施主的随机势的影响。我们诱导电子气静电，并能够改变至少7倍的表载流子密度（n（2D））。收缩显示了无共振整数电导平台和附加的“0.7结构”，一种平台状特征，其电导在低和高n（2D）下从约0.80减小到0.5 x 2 e（2）/h。该低值不受高面内磁场的影响，支持先前的证据和理论，即在高场下自旋简并的破坏以某种形式持续存在，即使是在零场。在高去偏压下，在电导约为0.85 x 2 e（2）/h时，通常看到的特征高度也会发生变化，我们表明，这与连接两个特征电导的简单关系是合理一致的。我们使用源漏偏压来研究最低的一维子带的自旋分裂，并发现第一个子带的自旋能隙与n（2D）无关。我们讨论了可能的原因分裂，并展示了各种模型的0.7结构可以应用在有限的偏置制度。
We have studied the transport propel-ties of a high quality one-dimensional constriction formed in an undoped GaAs/AlxGa1-xAs heterostructure and therefore largely free of the random potential of ionized donors. We induce an electron gas electrostatically and are able to vary the sheet carrier density (n(2D)) by a factor of at least seven. The constriction shows resonance-free integer conductance plateaus and the additional "0.7 structure," a plateaulike feature, the conductance of which decreases from about 0.80 towards 0.5 x 2e(2)/h at low and high n(2D) This low value is unaffected by a high in-plane magnetic field, supporting previous evidence and theories that the breaking of the spin degeneracy at high fields persists in some form, even at zero field. The height of the feature generally seen at a conductance of about 0.85 x 2 e(2)/h at high de bias also varies, and we show that this is in reasonable agreement with a simple relation linking the conductances of the two features. We use a source-drain bias to study the spin splitting of the lowest one-dimensional subbands, and find a spin gap that is independent of n(2D) for the first subband. We discuss possible reasons for the splitting, and show how various models for the 0.7 structure can be applied in the finite bias regime.