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arXiv 0811.4116cond-mat.mes-hall
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ν= 1/2 + 1/2量子霍尔双层膜的试探波函数

Trial Wavefunctions for ν= 1/2 + 1/2 Quantum Hall Bilayers

Gunnar Moller, Steven H Simon, Edward H Rezayi

摘要:

当层间距d减小到某一临界值以下时,填充率在ν= 1/2 + 1/2附近的量子霍尔双层系统经历了从具有强层内关联的可压缩相到具有强层间关联的不可压缩相的转变。在层内相深处(大分离),系统可以被解释为复合费米子(CF)的流体,而在层间相深处(小分离),系统可以被解释为复合玻色子(CB)的流体。本文的重点是理解的状态,发生的中间层分离,通过使用试验变分波函数。我们考虑两类主要的波函数。在第一类中,先前由Moller等人[PRL { \bf 101},176803(2008)]介绍,我们考虑两种独立CF液体的层间BCS配对。我们发现,当d >~ \ell_0且\ell_0为磁长时,这些波函数是非常好的.第二类波函数自然遵循Simon等人[PRL { \bf 91},046803(2003)]的推理,并且通过允许CF也被CB连续替换来推广配对波函数的思想。这种推广也使我们能够构造层间距d <~ \ell_0的非常好的波函数。在这项工作中讨论的波函数的准确性,精确对角化相比,著名的Laughlin波函数的方法。

英文摘要:

Quantum Hall bilayer systems at filling fractions near ν= 1/2 + 1/2 undergo a transition from a compressible phase with strong intralayer correlation to an incompressible phase with strong interlayer correlations as the layer separation d is reduced below some critical value. Deep in the intralayer phase (large separation) the system can be interpreted as a fluid of composite fermions (CFs), whereas deep in the interlayer phase (small separation) the system can be interpreted as a fluid of composite bosons (CBs). The focus of this paper is to understand the states that occur for intermediate layer separation by using trial variational wavefunctions. We consider two main classes of wavefunctions. In the first class, previously introduced by Moller et al. [PRL {\bf 101}, 176803 (2008)], we consider interlayer BCS pairing of two independent CF liquids. We find that these wavefunctions are exceedingly good for d >~ \ell_0 with \ell_0 the magnetic length. The second class of wavefunctions naturally follows the reasoning of Simon et al. [PRL {\bf 91}, 046803 (2003)] and generalizes the idea of pairing wavefunctions by allowing the CFs also to be replaced continuously by CBs. This generalization allows us to construct exceedingly good wavefunctions for interlayer spacings of d <~ \ell_0, as well. The accuracy of the wavefunctions discussed in this work, compared with exact diagonalization, approaches that of the celebrated Laughlin wavefunction.

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