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arXiv 2102.00548cond-mat.str-elcond-mat.mtrl-scicond-mat.othercond-mat.stat-mech
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了解在单带和双带二维电子气体中负电子压缩性的开始:应用于LaAlO $_3$ / SrTiO $_3$

Understanding the onset of negative electronic compressibility in one- and two-band 2D electron gases: Application to LaAlO$_3$/SrTiO$_3$

A. D. Mahabir, A. V. Balatsky, J. T. Haraldsen

摘要:

研究了二维电子气中两个电子带对负电子压缩性的影响。我们使用一个简单的均匀模型与库仑相互作用和一阶多带耦合的临界载流子密度,其中压缩性变成负的有效质量和相对介电常数的作用进行检查。我们证明,人口的第二个频带,随着带间耦合的存在下,可以显着地改变交叉载流子密度。考虑到确定和确认多波段电子系统的困难,该模型提供了一种潜在的方法,用于识别多波段电子系统,使用精确的体电子特性测量。为了帮助说明这种方法,我们将我们的结果应用到观察到的NEC在2D电子气在界面的LaAlO $_3$ /SrTiO $_3$(LAO/STO),并确定,对于已知的参数LAO/STO,该系统可能是一个实现的两个波段的2D电子气。此外,我们提供了一般限制带间耦合相对于电子带人口。

英文摘要:

We investigate the effects of two electronic bands at the negative electronic compressibility (NEC) in a two-dimensional electron gas (2DEG). We use a simple homogeneous model with Coulombic interactions and first-order multi-band coupling to examine the role of effective mass and relative permittivity in relation to the critical carrier density, where compressibility turns negative. We demonstrate that the population of a second band, along with the presence of inter-band coupling, can dramatically change the cross-over carrier density. Given the difficulty in determining and confirming multi-band electronic systems, this model provides a potential method for identifying multi-band electronic systems using precise bulk electronic properties measurements. To help illustrate this method, we apply our results to the observed NEC in the 2D electron gas at the interface of LaAlO$_3$/SrTiO$_3$ (LAO/STO) and determine that, for the known parameters of LAO/STO, the system is likely a realization of a two-band 2D electron gas. Furthermore, we provide general limits on the inter-band coupling with respect to the electronic band population.

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