强电子关联异质结构的电容和可压缩性
Capacitance and compressibility of heterostructures with strong electronic correlations
摘要：
在单带模型中，与排斥局域相互作用相关的强电子关联抑制了电子的可压缩性，相应金属薄膜的电容与其电子的可压缩性直接相关。这两种说法可能会改变显着时，两个扩展系统的实施，我们在这里调查：（一）我们引入了一个有吸引力的最近邻相互作用$V$作为拮抗剂的排斥性现场排斥$U$，及（ii）我们认为纳米结构的多层（异质结构）组装从二维层这些系统。我们确定各自的总压缩性$κ$和电容$C$的异质结构内的强耦合的评价，这是建立在Kotliar-Ruckenstein从玻色子技术。而电容$C(n)$的电子密度$n$接近半填充被抑制-说明了相关诱导下降$C(n)$ -它可能会明显增强接近范霍夫奇点。此外，我们表明，电容可能是一个非单调函数的$U$接近半填充的吸引力和排斥$V$。可压缩性$κ$可与$C$显著不同，因为$κ$对内部静电能非常敏感，而内部静电能又取决于异质结构的具体设置。特别是，我们表明，具有极性电介质的电容器具有较小的电子可压缩性，并且比具有相同电容的标准非极性电容器更稳定地对抗相分离。
英文摘要：
Strong electronic correlations related to a repulsive local interaction suppress the electronic compressibility in a single-band model, and the capacitance of a corresponding metallic film is directly related to its electronic compressibility. Both statements may be altered significantly when two extensions to the system are implemented which we investigate here: (i) we introduce an attractive nearest-neighbor interaction $V$ as antagonist to the repulsive on-site repulsion $U$, and (ii) we consider nano-structured multilayers (heterostructures) assembled from two-dimensional layers of these systems. We determine the respective total compressibility $κ$ and capacitance $C$ of the heterostructures within a strong coupling evaluation, which builds on a Kotliar-Ruckenstein slave-boson technique. Whereas the capacitance $C(n)$ for electronic densities $n$ close to half-filling is suppressed---illustrated by a correlation induced dip in $C(n)$---it may be appreciably enhanced close to a van Hove singularity. Moreover, we show that the capacitance may be a non-monotonic function of $U$ close to half-filling for both attractive and repulsive $V$. The compressibility $κ$ can differ from $C$ substantially, as $κ$ is very sensitive to internal electrostatic energies which in turn depend on the specific set-up of the heterostructure. In particular, we show that a capacitor with a polar dielectric has a smaller electronic compressibility and is more stable against phase separation than a standard non-polar capacitor with the same capacitance.
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