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arXiv 0808.2076cond-mat.mes-hall
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量子线中的维格纳晶体物理

Wigner crystal physics in quantum wires

Julia S. Meyer, K. A. Matveev

摘要:

近年来,量子线相互作用的物理学引起了人们的广泛关注。当导线中的电子密度很低时,电子之间的强烈排斥导致维格纳晶体的形成。我们回顾了维格纳晶体的丰富的自旋和轨道性质,无论是在一维和准一维制度。在一维维格纳晶体中,电子自旋形成一个具有指数小交换耦合的反铁磁海森堡链。在铅的存在下,所产生的电子密度的不均匀性导致违反自旋-电荷分离。因此,自旋自由度影响导线的电导。随着电子密度的增加,维格纳晶体开始偏离严格的一维几何形状,形成锯齿形结构。在这个制度中的自旋相互作用占主导地位的环交换,所得到的锯齿形自旋链的相图有一些非极化的阶段,以及区域的完全和部分自旋极化。最后我们讨论了从一维到准一维态的跃迁附近的轨道性质。由于锯齿形维格纳晶体中链之间的锁定,只有一个无隙模式存在。Wigner晶体物理在弱相互作用下的表现形式是通过研究作为相互作用强度的函数的附加带隙低能模的命运来探索的。

英文摘要:

The physics of interacting quantum wires has attracted a lot of attention recently. When the density of electrons in the wire is very low, the strong repulsion between electrons leads to the formation of a Wigner crystal. We review the rich spin and orbital properties of the Wigner crystal, both in the one-dimensional and quasi-one-dimensional regime. In the one-dimensional Wigner crystal the electron spins form an antiferromagnetic Heisenberg chain with exponentially small exchange coupling. In the presence of leads the resulting inhomogeneity of the electron density causes a violation of spin-charge separation. As a consequence the spin degrees of freedom affect the conductance of the wire. Upon increasing the electron density, the Wigner crystal starts deviating from the strictly one-dimensional geometry, forming a zigzag structure instead. Spin interactions in this regime are dominated by ring exchanges, and the phase diagram of the resulting zigzag spin chain has a number of unpolarized phases as well as regions of complete and partial spin polarization. Finally we address the orbital properties in the vicinity of the transition from a one-dimensional to a quasi-one-dimensional state. Due to the locking between chains in the zigzag Wigner crystal, only one gapless mode exists. Manifestations of Wigner crystal physics at weak interactions are explored by studying the fate of the additional gapped low-energy mode as a function of interaction strength.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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