Infrared Spectroscopy of Quantum Crossbars

TL;DR

This paper explores how infrared spectroscopy can probe quantum crossbars, revealing plasmon excitations, dimensional crossovers, and substrate interactions, with implications for understanding quantum wire networks at finite frequencies.

Contribution

It provides a detailed analysis of IR spectroscopy responses in quantum crossbars, highlighting the effects of wave vector direction, frequency, and substrate interactions on plasmon excitations.

Findings

Infrared spectroscopy reveals plasmon resonances in quantum crossbars.

Dimensional crossover effects depend on incident wave angle and frequency.

Substrate interactions modify dielectric losses and induce Landau damping.

Abstract

Infrared (IR) spectroscopy can be used as an important and effective tool for probing periodic networks of quantum wires or nanotubes (quantum crossbars, QCB) at finite frequencies far from the Luttinger liquid fixed point. Plasmon excitations in QCB may be involved in resonance diffraction of incident electromagnetic waves and in optical absorption in the IR part of the spectrum. Direct absorption of external electric field in QCB strongly depends on the direction of the wave vector ${\bf q}.$ This results in two types of $1D\to 2D$ dimensional crossover with varying angle of an incident wave or its frequency. In the case of QCB interacting with semiconductor substrate, capacitive contact between them does not destroy the Luttinger liquid character of the long wave QCB excitations. However, the dielectric losses on a substrate surface are significantly changed due to appearance of additional Landau damping. The latter is initiated by diffraction processes on QCB superlattice and manifests itself as strong but narrow absorption peaks lying below the damping region of an isolated substrate.Submi